Document:

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                                                                     EXHIBIT 4.1

                    NAVISTAR FINANCIAL SECURITIES CORPORATION

                                     SELLER

                         NAVISTAR FINANCIAL CORPORATION

                                    SERVICER

                                       AND

                              THE BANK OF NEW YORK

                              MASTER TRUST TRUSTEE

                ON BEHALF OF THE SERIES 2003-1 CERTIFICATEHOLDERS

                       ----------------------------------

                            SERIES 2003-1 SUPPLEMENT

                            DATED AS OF JULY 10, 2003

                                       TO

                         POOLING AND SERVICING AGREEMENT

                            DATED AS OF JUNE 8, 1995

                       ----------------------------------

   CLASS A, FLOATING RATE DEALER NOTE ASSET BACKED CERTIFICATES, SERIES 2003-1
   CLASS B, FLOATING RATE DEALER NOTE ASSET BACKED CERTIFICATES, SERIES 2003-1

                   NAVISTAR FINANCIAL DEALER NOTE MASTER TRUST

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                                TABLE OF CONTENTS
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ARTICLE I CREATION OF SERIES 2003-1 AND THE SERIES 2003-1 CERTIFICATES............................4
     SECTION 1.01  Designation....................................................................4

ARTICLE II DEFINITIONS............................................................................4
     SECTION 2.01  Definitions....................................................................4

ARTICLE III SERVICING FEE........................................................................18
     SECTION 3.01  Servicing Compensation18

ARTICLE IV RIGHTS OF SERIES 2003-1 CERTIFICATEHOLDERS AND
     ALLOCATION AND APPLICATION OF COLLECTIONS...................................................18
     SECTION 4.01  Rights of the Series 2003-1 Certificateholders................................18
     SECTION 4.02  Establishment of Series Principal Account, Spread Account and
                    Liquidity Reserve Account....................................................19
     SECTION 4.03  [Reserved.]...................................................................22
     SECTION 4.04  Application of Available Certificateholder Interest Collections...............22
     SECTION 4.05  Application of Available Seller's Finance Charge Collections,
                    Spread Account and Liquidity Reserve Account to Deficiency Amount............23
     SECTION 4.06  Certificateholder Charge-Offs.................................................24
     SECTION 4.07  Application of Seller's Finance Charge Collections............................24
     SECTION 4.08  Application of Series Allocable Principal Collections.........................25
     SECTION 4.09  Shared Principal Collections..................................................27
     SECTION 4.10  Distributions to Series 2003-1 Certificateholders.............................27
     SECTION 4.11  Accumulation Period Length; Accumulation Period Commencement Date.............28
     SECTION 4.12  Partial Month Due Period......................................................28
     SECTION 4.13  Additional Rights upon the Occurrence of Certain Events.......................28

ARTICLE V DISTRIBUTIONS AND REPORTS TO SERIES 2003-1 CERTIFICATEHOLDERS..........................29
     SECTION 5.01  Distributions.................................................................29
     SECTION 5.02  Monthly and Annual Certificateholders' Statement..............................29

ARTICLE VI EARLY AMORTIZATION EVENTS.............................................................31
     SECTION 6.01  Additional Early Amortization Events..........................................31

ARTICLE VII OTHER SERIES PROVISIONS..............................................................34
     SECTION 7.01  Conveyance of Dealer Notes....................................................34
     SECTION 7.02  Tax Treatment.................................................................34

ARTICLE VIII FINAL DISTRIBUTIONS.................................................................36
     SECTION 8.01  Sale of Investors' Interest Pursuant to Section 2.07 of the
                    Agreement; Distributions Pursuant to Section 2.03 or 12.03 of the
                    Agreement....................................................................36
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     SECTION 8.02  Distribution of Proceeds of Sale, Disposition or Liquidation of the
                    Dealer Notes Pursuant to Section 9.02 of the Agreement.......................36

ARTICLE IX MISCELLANEOUS PROVISIONS..............................................................38
     SECTION 9.01  Ratification of Agreement.....................................................38
     SECTION 9.02  Counterparts..................................................................38
     SECTION 9.03  GOVERNING LAW.................................................................38
     SECTION 9.04  Tax Disclosure................................................................38
     SECTION 9.05  Consent to Amendment..........................................................38
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EXHIBITS

Exhibit A-1  -   Form of Class A Certificate

Exhibit A-2  -   Form of Class B Certificate

Exhibit B    -   Form of Monthly Servicer and Settlement Statement

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                            SERIES 2003-1 SUPPLEMENT
                       TO POOLING AND SERVICING AGREEMENT

          SERIES 2003-1 SUPPLEMENT dated as of July 10, 2003 (the "Series
Supplement"), by and among NAVISTAR FINANCIAL SECURITIES CORPORATION, a Delaware
corporation, as Seller (the "Seller"), NAVISTAR FINANCIAL CORPORATION, a
Delaware corporation, as Servicer (the "Servicer"), and THE BANK OF NEW YORK, a
New York banking corporation, as trustee (together with its successors in trust
thereunder as provided in the Agreement referred to below, the "Master Trust
Trustee") under the Pooling and Servicing Agreement, dated as of June 8, 1995
(as amended and supplemented, the "Agreement") among the Seller, the Servicer
and the Master Trust Trustee.

          Section 6.09 of the Agreement provides that the Seller may from time
to time direct the Master Trust Trustee to issue, on behalf of the Master Trust,
one or more new Series of Investor Certificates representing fractional
undivided interests in the Master Trust. The Principal Terms of any new Series
are to be set forth in a Supplement to the Agreement.

          Pursuant to this Series Supplement, the Seller and the Master Trust
Trustee shall create a new Series of Investor Certificates and specify the
Principal Terms thereof.

                                    ARTICLE I
                          CREATION OF SERIES 2003-1 AND
                         THE SERIES 2003-1 CERTIFICATES

     SECTION 1.01  DESIGNATION.

          (a)  There is hereby created a new Series pursuant to the Agreement
and this Series Supplement to be known as the "Series 2003-1." The interest of
the Investor Certificateholders in Series 2003-1 shall be represented by the
"Class A Certificates" and the "Class B Certificates" (collectively, the "Series
2003-1 Certificates").

          (b)  If any term or provision contained herein shall conflict with or
be inconsistent with any term or provision contained in the Agreement, the terms
and provisions of this Series Supplement shall govern with respect to Series
2003-1.

                                   ARTICLE II
                                   DEFINITIONS

     SECTION 2.01  DEFINITIONS.

          (a)  Whenever used in this Series Supplement, the following words and
phrases shall have the following meanings:

          "ACCUMULATION PERIOD" shall mean, unless an Early Amortization Event
shall have occurred prior thereto, the period commencing on the Accumulation
Period Commencement Date and ending upon the first to occur of (a) the
commencement of an Early Amortization Period and (b) the payment of the Invested
Amount in full.

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          "ACCUMULATION PERIOD COMMENCEMENT DATE" shall mean the first day of
the Nth full Due Period prior to the Expected Principal Payment Date where N is
the number of Due Periods in the Accumulation Period Length; PROVIDED, HOWEVER,
that the Accumulation Period Commencement Date shall be the Specified
Accumulation Period Commencement Date if, on the Specified Accumulation Period
Commencement Date, any other outstanding Series shall have entered into an
investment period or an early amortization period; and PROVIDED FURTHER that, if
the Accumulation Period Length and the Accumulation Period Commencement Date
have been determined pursuant to SECTION 4.11 but the Accumulation Period has
not commenced and any other outstanding Series shall enter into an investment
period or an early amortization period, the Accumulation Period Commencement
Date shall be the date that such outstanding Series shall have entered into an
investment period or an early amortization period.

          "ACCUMULATION PERIOD LENGTH" shall mean a period which is between one
and nine Due Periods and which is determined by the Servicer pursuant to SECTION
4.11.

          "ADJUSTED INVESTED AMOUNT" shall mean, with respect to any
Distribution Date, an amount (which shall never be less than zero) equal to (1)
the sum of the Class A Initial Invested Amount, AND the Class B Initial Invested
Amount, PLUS (2) the Available Subordinated Amount as of the end of the related
Transfer Date, MINUS (3) the sum of (a) the aggregate amount of Class A
Certificateholder Charge-Offs not reimbursed on or prior to such Distribution
Date and (b) the aggregate amount of Class B Certificateholder Charge-Offs not
reimbursed on or prior to such Distribution Date; PROVIDED that, for purposes of
calculating the Series Allocation Percentage, the Series 2003-1 shall be deemed
to have been outstanding as of June 25, 2003 with respect to allocations of
Principal Collections and related concepts and as of June 25, 2003 with respect
to Finance Charge Collections and related concepts, in each case with an
Adjusted Invested Amount of $231,080,000.

          "AMORTIZING DUE PERIOD" shall have the meaning specified in SECTION
4.12.

          "AVAILABLE CERTIFICATEHOLDER INTEREST COLLECTIONS" shall mean, with
respect to any Due Period, the sum of (a) Investor Finance Charge Collections
for such Due Period and (b) Investment Income for that Due Period.

          "AVAILABLE DRAW FUNDS" shall have the meaning specified in SECTION
4.05(b).

          "AVAILABLE SELLER'S FINANCE CHARGE COLLECTIONS" shall mean, with
respect to any Due Period, an amount equal to the product of (a) the excess of
(i) the Seller's Percentage for such Due Period over (ii) the result (if
positive) of the Excess Seller's Percentage for such Due Period MINUS the
Required Excess Seller Interest Percentage and (b) Series Allocable Finance
Charge Collections for such Due Period; PROVIDED, HOWEVER, that Available
Seller's Finance Charge Collections shall be zero for any Due Period to the
extent the Available Subordinated Amount equals or is reduced to zero on the
Transfer Date related to such Due Period.

          "AVAILABLE SELLER'S PRINCIPAL COLLECTIONS" shall mean, with respect to
any Business Day, an amount equal to the product of (a) the excess of (i) the
Seller's Percentage for the Due Period in which such Business Day occurs over
(ii) the Excess Seller's Percentage for such Due Period and (b) Series Allocable
Principal Collections for such Business Day; PROVIDED, HOWEVER, that Available
Seller's Principal Collections shall be zero for any Business Day to the extent
the

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Available Subordinated Amount equals or is reduced to zero on the Transfer Date
immediately preceding such Business Day.

          "AVAILABLE SUBORDINATED AMOUNT" shall mean for the first Transfer Date
after the Closing Date, $19,080,000, and for each Transfer Date thereafter
(before giving effect to all adjustments in the Available Subordinated Amount
thereto on such Transfer Date), the lesser of (i) the Maximum Subordinated
Amount as of such Transfer Date and (ii) the Available Subordinated Amount as of
the end of the preceding Transfer Date.

          "AVERAGE COVERAGE DIFFERENTIAL" shall be determined, on any
Determination Date, by reference to the Coverage Differentials for each of the
related Due Period and the three immediately preceding Due Periods, and shall
equal the sum of the three highest such Coverage Differentials DIVIDED BY three.
Average Coverage Differential shall be expressed as a percentage, and shall be
rounded to the nearest one-hundredth of a percentage point.

          "BACK UP SERVICER TRIGGER EVENT" shall mean, with respect to Series
2003-1, any event specified in SECTION 7.03 of this Series Supplement.

          "BUSINESS DAY" shall mean, with respect to Series 2003-1, any day
other than a Saturday, a Sunday, or a day on which banking institutions in New
York, New York, Chicago, Illinois, or the city in which the Corporate Trust
Office is located, or in connection with the determination of LIBOR, London,
England, are authorized or obligated by law or executive order to be closed or
remain closed.

          "CERTIFICATEHOLDER CHARGE-OFF" shall have the meaning specified in
SECTION 4.06.

          "CLASS A CERTIFICATE RATE" shall mean the interest rate on the Class A
Certificates, which shall equal 1.41313% for the Initial Distribution Period and
for each Distribution Period thereafter will equal LIBOR as of the related LIBOR
Determination Date plus 0.30%.

          "CLASS A CERTIFICATEHOLDER CHARGE-OFF" shall have the meaning
specified in SECTION 4.06.

          "CLASS A CERTIFICATEHOLDERS" shall mean the holders of Class A
Certificates.

          "CLASS A CERTIFICATES" shall mean any one of the certificates executed
by the Seller and authenticated by the Master Trust Trustee, substantially in
the form of EXHIBIT A-1.

          "CLASS A INITIAL INVESTED AMOUNT" shall mean $200,000,000.

          "CLASS A INVESTED AMOUNT" shall mean, with respect to any Distribution
Date, an amount (which shall never be less than zero) equal to the Class A
Initial Invested Amount, MINUS the sum of (a) the aggregate amount of payments
of principal in respect of the Class A Certificates made to Class A
Certificateholders on or prior to such Distribution Date, (b) the aggregate
amount of Class A Certificateholder Charge-Offs not reimbursed pursuant to
SECTION 4.04(a)(v) on or prior to such Distribution Date, and (c) the aggregate
amount of Class A Principal Account Losses on or prior to such Distribution
Date.

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          "CLASS A MONTHLY INTEREST" shall mean, with respect to each Transfer
Date related to a Distribution Period, an amount equal to the product of (a) the
Class A Certificate Rate for such Distribution Period and (b) the Class A
Invested Amount (calculated without giving effect to clauses (b) and (c) of the
definition thereof) as of the preceding Distribution Date (or the Class A
Initial Invested Amount with respect to the first Transfer Date) and (c) a
fraction, which (i) with respect to the first Transfer Date, shall be equal to
46 DIVIDED BY 360 and (ii) with respect to each subsequent Transfer Date, shall
be equal to the actual number of days in the related Distribution Period divided
by 360.

          "CLASS A PRINCIPAL ACCOUNT LOSSES" means, with respect to any
Distribution Date, the amount of Series Principal Account Losses since the prior
Distribution Date that are not Class B Principal Account Losses, but not more
than the amount that would reduce the Class A Invested Amount to zero.

          "CLASS B CERTIFICATE RATE" shall mean the interest rate on the Class B
Certificates, which shall equal 2.31313% for the Initial Distribution Period and
for each Distribution Period thereafter will equal LIBOR as of the related LIBOR
Determination Date plus 1.20%.

          "CLASS B CERTIFICATEHOLDER CHARGE-OFF" shall have the meaning
specified in SECTION 4.06.

          "CLASS B CERTIFICATEHOLDERS" shall mean the holders of Class B
Certificates.

          "CLASS B CERTIFICATES" shall mean any one of the certificates executed
by the Seller and authenticated by the Master Trust Trustee, substantially in
the form of EXHIBIT A-2.

          "CLASS B INITIAL INVESTED AMOUNT" shall mean $12,000,000.

          "CLASS B INVESTED AMOUNT" shall mean, with respect to any Distribution
Date, an amount (which shall never be less than zero) equal to the Class B
Initial Invested Amount, MINUS the sum of (a) the aggregate amount of payments
of principal in respect of the Class B Certificates made to Class B
Certificateholders on or prior to such Distribution Date, (b) the aggregate
amount of Class B Certificateholder Charge-Offs not reimbursed pursuant to
SECTION 4.04(a)(vi) on or prior to such Distribution Date, and (c) the aggregate
amount of Class B Principal Account Losses on or prior to such Distribution
Date.

          "CLASS B MONTHLY INTEREST" shall mean, with respect to each Transfer
Date related to a Distribution Period, an amount equal to the product of (a) the
Class B Certificate Rate for such Distribution Period and (b) the Class B
Invested Amount (calculated without giving effect to clauses (b) and (c) of the
definition thereof) as of the preceding Distribution Date (or the Class B
Initial Invested Amount with respect to the first Transfer Date) and (c) a
fraction, which (i) with respect to the first Transfer Date, shall be equal to
46 DIVIDED BY 360 and (ii) with respect to each subsequent Transfer Date, shall
be equal to the actual number of days in the related Distribution Period divided
by 360.

          "CLOSING DATE" shall mean July 10, 2003.

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          "CLASS B PRINCIPAL ACCOUNT LOSSES" means, with respect to any
Distribution Date, the amount of Series Principal Account Losses since the prior
Distribution Date, but not more than the amount that would reduce the Class B
Invested Amount to zero.

          "COMMON DEPOSITORY" shall mean Cede & Co.

          "CONTROLLED AMORTIZATION AMOUNT" shall mean an amount equal to the
result of (a) the Invested Amount as of the Distribution Date preceding the
Specified Accumulation Period Commencement Date DIVIDED BY (b) the Accumulation
Period Length.

          "CONTROLLED DEPOSIT AMOUNT" shall mean, with respect to any Due Period
occurring during the Accumulation Period, the excess, if any, of (a) the product
of (i) the Controlled Amortization Amount and (ii) the number of Due Periods
that have elapsed with respect to the Accumulation Period through and including
that Due Period (but not in excess of the Accumulation Period Length) over (b)
the amount on deposit in the Series Principal Account at the close of business
on the last Business Day of the preceding Due Period; PROVIDED, HOWEVER, that,
notwithstanding the foregoing, the Seller may, in its sole discretion, increase
the Controlled Deposit Amount at any time and from time to time.

          "COVERAGE DIFFERENTIAL" shall mean, with respect to any Due Period,
the result of (a) the Portfolio Yield for such Due Period MINUS (b) the sum of
(i) the Weighted Average Certificate Rate for the related Distribution Period
and (ii) one percent (1%). Coverage Differential shall be expressed as a
percentage, and shall be rounded to the nearest one-hundredth of a percentage
point.

          "DEFICIENCY AMOUNT" shall have the meaning specified in SECTION
4.05(a).

          "DRAW AMOUNT" shall mean, with respect to any Transfer Date, the least
of (a) the Deficiency Amount for such Transfer Date, (b) the Available
Subordinated Amount as of the end of the preceding Transfer Date and (c)
Available Draw Funds for such Transfer Date.

          "EARLY AMORTIZATION EVENT" shall mean, with respect to Series 2003-1,
any event specified in SECTION 9.01(c) of the Agreement, together with any
additional Early Amortization Event specified in SECTION 6.01 of this Series
Supplement, but shall not mean any other event specified in SECTION 9.01 of the
Agreement.

          "EARLY AMORTIZATION PERIOD" shall mean an Early Amortization Period
with respect to Series 2003-1 that occurs as a result of any event specified in
SECTION 9.01(c) of the Agreement or any Early Amortization Event specified in
SECTION 6.01 of this Series Supplement.

          "EARLY AMORTIZATION PERIOD SHORTFALL AMOUNT" shall have the meaning
specified in SECTION 4.08(e).

          "ELIGIBLE INVESTMENTS" shall mean

          (a)  book-entry securities, negotiable instruments or securities
represented by instruments in bearer or registered form having (except in the
case of clause (iv) below) remaining maturities occurring not later than the
Distribution Date next succeeding the Master Trust Trustee's acquisition
thereof, except as otherwise described herein, that evidence:

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               (i)     direct obligations of, and obligations fully guaranteed
               as to timely payment by, the United States of America;

               (ii)    demand deposits, time deposits or certificates of deposit
               of, or bankers' acceptances issued by, any depository institution
               or trust company incorporated under the laws of the United States
               of America or any state thereof (or any domestic branch of a
               foreign bank) and subject to supervision and examination by
               federal or state banking or depository institution authorities;
               PROVIDED, HOWEVER, that at the time of the Master Trust's
               investment or contractual commitment to invest therein, the
               commercial paper or other short-term unsecured debt obligations
               (other than such obligations the rating of which is based on the
               credit of a person or entity other than such depository
               institution or trust company) of such depository institution or
               trust company shall have a credit rating not lower than the
               highest investment category for short term unsecured debt
               obligations granted by the applicable Rating Agency from each
               Rating Agency then Rating the affected Series of Investor
               Certificates;

               (iii)   commercial paper having, at the time of the Master
               Trust's investment or contractual commitment to invest therein, a
               rating not lower than the highest investment category for short
               term unsecured debt obligations granted by the applicable Rating
               Agency from each Rating Agency then Rating the affected Series of
               Investor Certificates;

               (iv)    investments in money market funds or common trust funds
               having a rating not lower than the highest investment category
               for short term unsecured debt obligations granted by the
               applicable Rating Agency from each Rating Agency then Rating the
               affected Series of Investor Certificates or otherwise approved in
               writing by each of such Rating Agencies (including funds for
               which the Master Trust Trustee or any of its affiliates is
               investment manager or advisor, so long as such fund shall have
               such rating);

               (v)     repurchase obligations (x) with respect to any security
               that is a direct obligation of, or fully guaranteed by, the
               United States of America or any agency or instrumentality thereof
               the obligations of which are backed by the full faith and credit
               of the United States of America, in either case, entered into
               with a depository institution or trust company (acting as
               principal) described in clause (ii) or (y) the counterparty for
               which has a rating not lower than the highest investment category
               for short term unsecured debt obligations granted by the
               applicable Rating Agency from each Rating Agency then Rating the
               affected Series of Investor Certificates, the collateral for
               which is held by a custodial bank for the benefit of the Master
               Trust or the Master Trust Trustee, is marked to market daily and
               is maintained in an amount that exceeds the amounts of such
               repurchase obligation, and which required liquidation of the
               collateral immediately upon the amount of such collateral being
               less than the amount of such repurchase obligation (unless the
               counterparty immediately satisfies the repurchase obligation upon
               being notified of such shortfall); or

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               (vi)    commercial paper master notes where the issuer has, at
               the time of the Master Trust's investment or contractual
               commitment to invest therein, a rating not lower than the highest
               investment category for short term unsecured debt obligations
               granted by the applicable Rating Agency from each Rating Agency
               then Rating the Series 2003-1; and

          (b)  any other investment consisting of a financial asset that by its
terms converts to cash within a finite period of time, provided that the Rating
Agency Condition is satisfied.

          Unless the Rating Agency Condition is satisfied, Eligible Investments
of funds in the Series Principal Account and the Liquidity Reserve Account will
be subject to the following additional restrictions: (x) no more than the
greater of (A) $1,000,000 and (B) 20% of the aggregate Eligible Investments in
all such accounts collectively shall be obligations of or investments in any
single issuer (except that such 20% limitation shall not apply to Eligible
Investments of the type specified in clause (a)(i)); and (y) each Eligible
Investment shall be denominated and be payable solely in U.S. dollars, shall
bear interest at a specified rate that is, or is based upon, LIBOR or a
commercial paper rate, shall entitle the holder to a fixed principal amount at
maturity and shall have a yield that is not inversely or disproportionately
affected by changes in interest rates.

          "EXCESS SELLER'S PERCENTAGE" shall mean, with respect to any Due
Period, a percentage (which percentage shall never be less than 0% nor more than
100%) equal to the excess of (a) the Seller's Percentage for such Due Period,
over (b) the percentage equivalent (which percentage shall never be less than 0%
nor more than 100%) of a fraction, the numerator of which is the Available
Subordinated Amount as of the end of the related Transfer Date and the
denominator of which is the product of (x) the sum of the aggregate principal
amount of Dealer Notes in the Master Trust and the aggregate principal amount of
funds on deposit in the Excess Funding Account, both as of the end of the
immediately preceding Due Period and (y) the Series 2003-1 Allocation Percentage
for the Due Period for which the Excess Seller's Percentage is being calculated.

          "EXCESS SELLER'S PRINCIPAL COLLECTIONS" shall mean, with respect to
any Business Day during a Due Period, the product of (a) Series Allocable
Principal Collections for such Business Day and (b) the Excess Seller's
Percentage for such Due Period.

          "EXPECTED PRINCIPAL PAYMENT DATE" shall mean June 26, 2006.

          "FLOATING ALLOCATION PERCENTAGE" shall mean, with respect to any Due
Period , the percentage equivalent (which percentage shall never exceed 100%) of
a fraction, the numerator of which is the Invested Amount as of the immediately
preceding Distribution Date (after giving effect to all increases and reductions
thereof on such Distribution Date) and the denominator of which is the product
of (a) the sum of the aggregate principal amount of Dealer Notes in the Master
Trust and the aggregate principal amount of funds on deposit in the Excess
Funding Account, both as of the end of the immediately preceding Due Period, and
(b) the Series 2003-1 Allocation Percentage for the Due Period for which the
Floating Allocation Percentage is being calculated.

          "INITIAL DISTRIBUTION PERIOD" shall mean the period from July 10, 2003
through August 24, 2003.

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          "INITIAL INVESTED AMOUNT" shall mean the sum of the Class A Initial
Invested Amount and the Class B Initial Invested Amount.

          "INITIAL SPREAD ACCOUNT REQUIRED AMOUNT" shall mean $2,650,000.

          "INVESTED AMOUNT" shall mean, with respect to any Distribution Date,
the sum of the Class A Invested Amount as of such Distribution Date and the
Class B Invested Amount as of such Distribution Date.

          "INVESTMENT INCOME" shall mean, for any Due Period with respect to
Series 2003-1, the sum of (i) income (net of investment expenses and losses)
during such Due Period from the investment of funds on deposit in the Series
Principal Account, the Distribution Account maintained for the Series 2003-1
Certificateholders and the Spread Account and (ii) the product of (a) the Series
Allocation Percentage for such Due Period and (b) income (net of investment
expenses and losses) from the investment of funds on deposit in the Collections
Account and the Excess Funding Account.

          "INVESTOR DEALER NOTE LOSSES" shall mean, with respect to any Due
Period , the product of (a) the Floating Allocation Percentage for such Due
Period and (b) Series Allocable Dealer Note Losses for such Due Period.

          "INVESTOR FINANCE CHARGE COLLECTIONS" shall mean, with respect to any
Due Period, an amount equal to the product of (a) the Floating Allocation
Percentage for such Due Period and (b) Series Allocable Finance Charge
Collections for such Due Period.

          "INVESTOR PRINCIPAL COLLECTIONS" shall mean, with respect to any
Business Day, the sum of (a) the product of (i) with respect to the Revolving
Period, the Floating Allocation Percentage and with respect to the Accumulation
Period or any Early Amortization Period, the Principal Allocation Percentage, in
either case for the Due Period in which such Business Day occurs and (ii) Series
Allocable Principal Collections for such Business Day and (b) on any Transfer
Date, the amount, if any, of Available Certificateholder Interest Collections
treated as Investor Principal Collections pursuant to SECTIONS 4.04(a)(iv), (v)
and (vi).

          "INVESTOR SERVICING FEE" shall have the meaning specified in SECTION
3.01.

          "ITEC" shall mean International Truck and Engine Corporation (formerly
known as Navistar International Transportation Corp.).

          "LIBOR" shall mean the interest rate determined by the Master Trust
Trustee in accordance with the following provisions:

          (i)  On each LIBOR Determination Date, LIBOR will be determined on the
     basis of the offered rates for deposits in United States Dollars having a
     one month maturity, which appear on the Reuters Screen LIBO Page as of
     11:00 A.M., London time, on such LIBOR Determination Date. Such posted
     offered rates are for value on the second Business Day after which dealings
     in deposits in United States Dollars are transacted in the London interbank
     market. If at least two such offered rates appear on the Reuters Screen
     LIBO Page, the rate in respect of such LIBOR Determination Date will be the
     arithmetic mean (rounded, if necessary, to the nearest one
     hundred-thousandth of a percent) of such offered rates as determined by the
     Master Trust Trustee. If fewer than two offered rates appear, LIBOR in

                                      -11-
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     respect of such LIBOR Determination Date will be determined as if the
     parties had specified the rate described in (ii) below.

          (ii) On any LIBOR Determination Date on which fewer than two offered
     rates appear on the Reuters Screen LIBO Page as specified in (i) above,
     LIBOR will be determined on the basis of the rates at which deposits in
     United States Dollars are offered by the Reference Banks at approximately
     11:00 A.M., London time, on such LIBOR Determination Date to prime banks in
     the London interbank market, having a one month maturity, such deposits
     commencing on the second Business Day immediately following such LIBOR
     Determination Date and in a principal amount of not less than U.S.
     $1,000,000 that is representative for a single transaction in such market
     at such time. The Master Trust Trustee will request the principal London
     office of each of such Reference Banks to provide a quotation of its rate.
     If at least two such quotations are provided, LIBOR in respect of such
     LIBOR Determination Date will be the arithmetic mean (rounded, if
     necessary, to the nearest one hundred-thousandth of a percent) of such
     quotations. If fewer than two quotations are provided, LIBOR in respect of
     such LIBOR Determination Date will be the arithmetic mean (rounded, if
     necessary, to the nearest one hundred-thousandth of a percent) of the rates
     quoted by three major banks in The City of New York selected by the Master
     Trust Trustee at approximately 11:00 A.M., New York City time, on such
     LIBOR Determination Date for loans in United States Dollars to leading
     European banks, having a one month maturity, such loans commencing on the
     second Business Day immediately following such LIBOR Determination Date and
     in a principal amount of not less than U.S. $1,000,000 that is
     representative for a single transaction in such market at such time,
     provided, however, that if the banks in The City of New York selected as
     aforesaid by the Master Trust Trustee are not quoting as mentioned in this
     sentence, LIBOR with respect to such LIBOR Determination Date will be LIBOR
     in effect immediately prior to such LIBOR Determination Date.

          "LIBOR DETERMINATION DATE" shall mean, with respect to any
Distribution Period, the date which is two Business Days prior to the start of
such Distribution Period, or with respect to the Initial Distribution Period is
July 8, 2003.

          "LIQUIDITY RESERVE ACCOUNT" shall have the meaning specified in
SECTION 4.02(c)(i).

          "MAXIMUM SUBORDINATED AMOUNT" shall mean, with respect to any Transfer
Date, the product of (a) the Invested Amount as of the preceding Distribution
Date and (b) the Subordinated Percentage; PROVIDED, HOWEVER, that with respect
to a Transfer Date related to a Due Period occurring during an Early
Amortization Period, the Maximum Subordinated Amount shall not decline until the
Invested Amount equals the Maximum Subordinated Amount, and thereafter the
Maximum Subordinated Amount shall equal the Invested Amount.

          "MINIMUM SERIES 2003-1 SELLER'S INTEREST" shall mean, with respect to
any Business Day, the sum of (a) the Available Subordinated Amount as of the end
of the preceding Transfer Date and (b) the Required Excess Seller Interest as of
the end of the preceding Distribution Date.

          "MONTHLY SERVICING FEE" shall have the meaning specified in SECTION
3.01.

          "NEW VEHICLE MONTHLY INTEREST RATE" shall mean, with respect to any
Due Period, the product of (a) the per annum rate of interest and finance
charges billed by NFC during such Due

                                      -12-
<Page>

Period on New Vehicle Dealer Notes and (b) the quotient of (i) the number of
days during such Due Period and (ii) the actual number of days in the related
calendar year.

          "PORTFOLIO YIELD" shall mean, with respect to any Due Period, the
product of (a) the quotient of (i) Finance Charges for such Due Period and (ii)
the daily average principal amount of Dealer Notes outstanding during such Due
Period and (b) a fraction, the numerator of which is 365 and the denominator of
which is the actual number of days elapsed during such Due Period. Portfolio
Yield shall be expressed as a percentage, and shall be rounded to the nearest
one-hundredth of a percentage point.

          "PRINCIPAL ALLOCATION PERCENTAGE" shall mean, with respect to any Due
Period occurring during the Accumulation Period or any Early Amortization
Period, the percentage equivalent (which percentage shall never exceed 100%) of
a fraction, the numerator of which is the Invested Amount as of the end of the
Revolving Period and the denominator of which is equal to the product of (a) the
sum of the aggregate amount of Dealer Notes in the Master Trust and the
aggregate principal amount of funds on deposit in the Excess Funding Account,
both as of the end of the Revolving Period and (b) the Series 2003-1 Allocation
Percentage for the Due Period for which the Principal Allocation Percentage is
being calculated.

          "PRINCIPAL SHORTFALL" shall mean, with respect to Series 2003-1, the
Series 2003-1 Principal Shortfall.

          "PROJECTED DEALER NOTE INCOME" shall mean, on any Transfer Date, an
amount equal to the sum of (a) the product of (i) the principal amount of Dealer
Notes financing new vehicles outstanding on such Transfer Date, (ii) the New
Vehicle Monthly Interest Rate for the Due Period in which such Transfer Date
occurs and (iii) the Series 2003-1 Allocation Percentage for such Due Period and
(b) the product of (i) the principal amount of Dealer Notes financing used
vehicles outstanding on such Transfer Date, (ii) the Used Vehicle Monthly
Interest Rate for such Due Period and (iii) the Series 2003-1 Allocation
Percentage for such Due Period.

          "PROJECTED MONTHLY INTEREST" shall mean, on any Transfer Date with
respect to the Distribution Period immediately following such Transfer Date, an
amount equal to the sum of (1) the product of (A) the Class A Certificate Rate
for the Distribution Period immediately following such Transfer Date, (B) the
Class A Invested Amount (calculated without giving effect to clauses (b) and (c)
of the definition thereof) as of such Transfer Date and (C) the result of (i)
the actual number of days in such immediately following Distribution Period
divided by (ii) 360 and (2) the product of (A) the Class B Certificate Rate for
the Distribution Period immediately following such Transfer Date, (B) the Class
B Invested Amount (calculated without giving effect to clauses (b) and (c) of
the definition thereof) as of such Transfer Date and (C) the result of (i) the
actual number of days in such immediately following Distribution Period divided
by (ii) 360.

          "PROJECTED MONTHLY SERVICING FEE" shall mean, on any Transfer Date
with respect to the Due Period in which such Transfer Date occurs, an amount
equal to one-twelfth of the product of (a) 1%, (b) the aggregate principal
amount of Dealer Notes as of such Transfer Date, (c) the Series 2003-1
Allocation Percentage for the Due Period related to such Transfer Date and (d)
the Floating Allocation Percentage for the Due Period related to such Transfer
Date.

          "PROJECTED SPREAD" shall mean, on any Transfer Date with respect to
the Distribution Period next following the Distribution Period to which such
Transfer Date relates, the sum of (a) the

                                      -13-
<Page>

positive amount, if any, by which (i) the sum of (A) Projected Monthly Interest
for such Distribution Period and (B) the Projected Monthly Servicing Fee for the
Due Period in which such Transfer Date occurs exceeds (ii) the Projected Dealer
Note Income as of such Transfer Date and (b) 1.25% of the Invested Amount as of
the preceding Distribution Date.

          "REASSIGNMENT AMOUNT" shall mean, with respect to any Distribution
Date, after giving effect to any deposits and distributions otherwise to be made
on such Distribution Date, the sum of (a) the Invested Amount on such
Distribution Date, and (b) accrued and unpaid interest thereon.

          "REFERENCE BANKS" shall mean the principal London offices of JPMorgan
Chase Bank, Citibank and Bank of America.

          "REMAINING AVAILABLE SELLER'S PRINCIPAL CALCULATIONS" shall have the
meaning specified in SECTION 4.08(d).

          "REQUIRED EXCESS SELLER INTEREST" shall mean, with respect to any
Business Day, 3.0% of the Invested Amount as of the end of the preceding
Distribution Date (and such percentage shall be the "REQUIRED EXCESS SELLER
INTEREST PERCENTAGE").

          "REQUIRED SUBORDINATED AMOUNT" shall mean, with respect to any
Transfer Date related to a Due Period, an amount equal to 79.0% of the Maximum
Subordinated Amount as of such Transfer Date.

          "REVOLVING DUE PERIOD" shall have the meaning specified in SECTION
4.12.

          "REVOLVING PERIOD" shall mean, unless an Early Amortization Event
shall have occurred prior thereto, the period beginning on the Closing Date and
ending on the earlier of (a) the close of business on the Business Day
immediately preceding the Accumulation Period Commencement Date and (b) the
close of business on the Business Day immediately preceding the day on which an
Early Amortization Event occurs.

          "SELLER'S PERCENTAGE" shall mean, with respect to any Due Period, 100%
MINUS (a) the Floating Allocation Percentage for such Due Period, when used with
respect to Finance Charge Collections and Dealer Note Losses at all times or
Principal Collections during the Revolving Period, and (b) the Principal
Allocation Percentage for such Due Period, when used with respect to Principal
Collections during the Accumulation Period or any Early Amortization Period,
PROVIDED, HOWEVER, such percentage shall never be less than 0% nor more than
100%.

          "SELLER'S PRINCIPAL COLLECTIONS" shall mean, with respect to any
Business Day, an amount equal to the sum of (a) Available Seller's Principal
Collections for such Business Day and (b) Excess Seller's Principal Collections
for such Business Day.

          "SERIES 2003-1" shall mean the Series of Investor Certificates, the
terms of which are specified in this Series Supplement.

          "SERIES 2003-1 ACCOUNTS" shall mean, collectively, the Series
Principal Account, the Distribution Account maintained for the Series 2003-1
Certificateholders, the Liquidity Reserve Account and the Spread Account.

                                      -14-
<Page>

          "SERIES 2003-1 ACCUMULATION PERIOD PRINCIPAL SHORTFALL" shall mean,
with respect to any Business Day occurring during the Accumulation Period, the
excess, if any, of the Controlled Deposit Amount for the Due Period in which
such Business Day occurs over the amount of Investor Principal Collections
deposited in the Series Principal Account on such Business Day when added to the
amount of Investor Principal Collections previously deposited in the Series
Principal Account during such Due Period.

          "SERIES 2003-1 ALLOCATION PERCENTAGE" shall mean the Series Allocation
Percentage with respect to Series 2003-1.

          "SERIES 2003-1 CERTIFICATEHOLDERS" shall mean the Class A
Certificateholders and the Class B Certificateholders.

          "SERIES 2003-1 CERTIFICATEHOLDERS' INTEREST" shall mean that portion
of the Certificateholders' Interest evidenced by the Series 2003-1 Certificates.

          "SERIES 2003-1 CERTIFICATES" shall mean the Class A Certificates and
the Class B Certificates.

          "SERIES 2003-1 PRINCIPAL SHORTFALL" shall equal either (a) with
respect to any Business Day occurring during the Accumulation Period, the Series
2003-1 Accumulation Period Principal Shortfall or (b) with respect to any
Business Day during any Early Amortization Period, the excess, if any, of the
Invested Amount (reduced by (i) amounts on deposit in the Series Principal
Account and (ii) the aggregate amount of Series Principal Account Losses for the
Due Period in which such Business Day occurs) as of the immediately preceding
Distribution Date over Investor Principal Collections for such Business Day.

          "SERIES 2003-1 RATING AGENCY CONDITION" shall mean, with respect to
any action, that each Rating Agency shall have notified the Seller, the
Servicer, and the Master Trust Trustee in writing that such action will not
result in a reduction or withdrawal of the rating of the Series 2003-1
Certificates with respect to which it is a Rating Agency.

          "SERIES 2003-1 SHARED PRINCIPAL COLLECTIONS" shall have the meaning
specified in SECTION 4.09(b).

          "SERIES 2003-1 SHARED SELLER PRINCIPAL COLLECTIONS" shall have the
meaning specified in SECTION 4.08(d)(iv).

          "SERIES ALLOCABLE DEALER NOTE LOSSES" shall mean, with respect to any
Due Period, the product of (a) the Series 2003-1 Allocation Percentage for such
Due Period and (b) Dealer Note Losses for such Due Period.

          "SERIES ALLOCABLE FINANCE CHARGE COLLECTIONS" shall mean, with respect
to any Due Period, the product of (a) the Series 2003-1 Allocation Percentage
for such Due Period and (b) the amount of Finance Charge Collections for such
Due Period.

          "SERIES ALLOCABLE PRINCIPAL COLLECTIONS" shall mean, with respect to
any Business Day, the sum of (a) the product of (i) the Series 2003-1 Allocation
Percentage for the related Due Period and (ii) the amount of Principal
Collections deposited in the Collections Account on such

                                      -15-
<Page>

Business Day and (b) if the Accumulation Period Commencement Date occurs on such
Business Day, the product of (i) the Series 2003-1 Allocation Percentage for
such Due Period and (ii) the amount of funds on deposit in the Excess Funding
Account on such Accumulation Period Commencement Date.

          "SERIES INVESTED AMOUNT" shall mean, with respect to Series 2003-1,
the Invested Amount.

          "SERIES PRINCIPAL ACCOUNT" shall have the meaning specified in SECTION
4.02(a)(i).

          "SERIES PRINCIPAL ACCOUNT LOSSES" shall mean losses of principal on
investment of funds in the Series Principal Account.

          "SERIES TERMINATION DATE" shall mean June 25, 2009.

          "SERVICER TRANSITION FEE ACCOUNT" shall have the meaning specified in
SECTION 4.02(d).

          "SERVICER TRANSITION FEE ACCOUNT REQUIRED DEPOSIT AMOUNT" shall mean,
during the period from the Closing Date until the Servicer delivers its first
set of estimates pursuant to Section 7.04 of the Series Supplement, $100,000,
and with respect to any Business Day thereafter, the amount equal to the sum of
(a) if a Back Up Servicer has not yet been appointed and paid to map NFC's
servicing computer system with respect to the Dealer Notes, the product of (i)
the average of the estimates most recently delivered to the Master Trustee of
the fees and expenses of such Back Up Servicer to map the NFC servicing computer
system with respect to Dealer Notes and (ii) 1.5 and (b) if a Successor Servicer
has not yet been appointed and paid its set up fees and costs to assume the role
of Successor Servicer, the product of (i) the average of the estimates most
recently delivered to the Master Trustee of the set up and servicing transition
fees and costs of appointing a Successor Servicer and having such Successor
Servicer assume the role of Successor Servicer and (ii) 1.5, but the sum of (a)
and (b) to not be less than $100,000, PROVIDED, HOWEVER, if a Successor Servicer
shall have been appointed and paid its set up fees and costs the Servicer
Transition Fee Required Deposit Amount shall be $0.

          "SPECIFIED ACCUMULATION PERIOD COMMENCEMENT DATE" shall mean September
1, 2005.

          "SPREAD ACCOUNT" shall have the meaning specified in SECTION
4.02(b)(i).

          "SPREAD ACCOUNT DEPOSIT AMOUNT" shall mean, with respect to any
Transfer Date prior to the commencement of an Early Amortization Period, the
amount, if any, by which the Projected Spread for that Transfer Date exceeds the
amount of funds on deposit in the Spread Account.

          "SUBJECT MONTH" shall have the meaning specified in SECTION 4.12.

          "SUBORDINATED PERCENTAGE" shall mean 9.0%.

          "TRANSACTIONS" shall have the meaning specified in SECTION 9.04.

                                      -16-
<Page>

          "TURNOVER" shall have the meaning specified in SECTION 6.01(k).

          "USED VEHICLE MONTHLY INTEREST RATE" shall mean, with respect to any
Due Period, the product of (i) the per annum rate of interest and finance
charges billed by NFC during such Due Period on Used Vehicle Dealer Notes and
(ii) the quotient of (a) a number equal to the number of days during such Due
Period and (b) the actual number of days in the related calendar year.

          "WEIGHTED AVERAGE CERTIFICATE RATE" shall mean, for any Distribution
Period, the sum of (i) the Class A Certificate Rate for such Distribution
Period, multiplied by a fraction, (a) the numerator of which is the Class A
Invested Amount as of the first day of such Distribution Period and (b) the
denominator of which is the Invested Amount as of the first day of such
Distribution Period, PLUS (ii) the Class B Certificate Rate for such
Distribution Period, multiplied by a fraction, (a) the numerator of which is the
Class B Invested Amount as of the first day of such Distribution Period and (b)
the denominator of which is the Invested Amount as of the first day of such
Distribution Period.

          (b)  Notwithstanding anything to the contrary in this Series
Supplement or the Agreement, the term "Rating Agency" shall mean, whenever used
in this Series Supplement or the Agreement with respect to Series 2003-1,
Moody's and Standard & Poor's. As used in this Series Supplement and in the
Agreement with respect to Series 2003-1, "highest investment category" shall
mean (i) in the case of Standard & Poor's, A-1+, AAA, AAAm, or AAAm-G, as
applicable, and (ii) in the case of Moody's, P-1 or Aaa, as applicable.

          (c)  All capitalized terms used herein and not otherwise defined
herein have the same meanings ascribed to them in the Agreement.

          (d)  The words "hereof," "herein" and "hereunder" and words of similar
import when used in this Series Supplement shall refer to this Series Supplement
as a whole and not to any particular provision of this Series Supplement;
references to any Article, Section or Exhibit are references to Articles,
Sections and Exhibits in or to this Series Supplement unless otherwise
specified; and the term "including" means "including without limitation."

          (e)  As used in this Series Supplement, references to the Available
Subordinated Amount "as of the end" of a Transfer Date shall mean the Available
Subordinated Amount as of such Transfer Date, after giving effect to all
increases and reductions thereof pursuant to Article IV hereof.

          (f)  As used in this Series Supplement, accounting terms which are not
defined, and accounting terms partly defined, herein shall have the respective
meanings given to them under generally accepted accounting principles as in
effect on the date hereof. To the extent that the definitions of accounting
terms in this Series Supplement are inconsistent with the meanings of such terms
under generally accepted accounting principles, the definitions contained in
this Series Supplement will control.

          (g)  With respect to any Distribution Date or Transfer Date, the
"related Due Period" and the "related Distribution Period" will mean the Due
Period and Distribution Period, respectively, immediately preceding such
Distribution Date or Transfer Date, and the relationships between Due Periods
and Distribution Periods will be correlative to the foregoing relationships.
With respect to any LIBOR Determination Date, the "related Distribution Period"
will mean the

                                      -17-
<Page>

Distribution Period beginning on the Distribution Date immediately following
such LIBOR Determination Date.

          (h)  Each defined term used in this Series Supplement has a comparable
meaning when used in its plural or singular form. Each gender-specific term used
in this Series Supplement has a comparable meaning whether used in a masculine,
feminine or gender-neutral form.

                                   ARTICLE III
                                  SERVICING FEE

     SECTION 3.01 SERVICING COMPENSATION. The monthly servicing fee (the
"Monthly Servicing Fee") shall be payable to the Servicer, in arrears, on each
Distribution Date in respect of a Due Period (or portion thereof) occurring
prior to the earlier of the first Distribution Date following the Series
Termination Date and the first Distribution Date on which the Invested Amount is
zero, in an amount equal to one-twelfth of the result of (a) 1% MULTIPLIED BY
(b) the aggregate principal amount of Dealer Notes outstanding as of the last
day of such Due Period and MULTIPLIED BY (c) the Series 2003-1 Allocation
Percentage with respect to such Due Period. The share of the Monthly Servicing
Fee allocable to the Series 2003-1 Certificateholders with respect to any
Transfer Date (the "Investor Servicing Fee") shall be equal to the product of
(a) the Monthly Servicing Fee and (b) the Floating Allocation Percentage with
respect to such Due Period. The remainder of the Monthly Servicing Fee shall be
paid by the Seller and in no event shall the Master Trust, the Master Trust
Trustee or the Series 2003-1 Certificateholders be liable for the share of the
Monthly Servicing Fee to be paid by the Seller; and the remainder of the
Servicing Fee shall be paid by the Seller and the Investor Certificateholders of
other Series and the Series 2003-1 Certificateholders shall in no event be
liable for the share of the Servicing Fee to be paid by the Seller or the
Investor Certificateholders of other Series. The Investor Servicing Fee shall be
payable to the Servicer solely to the extent amounts are available for
distribution in accordance with the terms of this Series Supplement.

          The Servicer will be permitted, in its sole discretion, to waive the
Monthly Servicing Fee for any Distribution Date by notice to the Master Trust
Trustee on or before the related Determination Date; PROVIDED, HOWEVER, that the
Servicer believes that sufficient Series Allocable Finance Charge Collections
will be available on any future Distribution Date to pay the Investor Servicing
Fee relating to the waived Monthly Servicing Fee. If the Servicer so waives the
Monthly Servicing Fee for any Distribution Date, the Monthly Servicing Fee and
the Investor Servicing Fee for such Distribution Date shall be deemed to be zero
for all purposes of this Series Supplement and the Agreement; PROVIDED, HOWEVER,
that such Investor Servicing Fee shall be paid on a future date solely to the
extent amounts are available therefor pursuant to SECTION 4.04(a)(viii); and
PROVIDED FURTHER that, to the extent any such waived Investor Servicing Fee is
so paid, the related portion of the Monthly Servicing Fee to be paid by the
Seller shall be paid by the Seller to the Servicer.

                                   ARTICLE IV
                   RIGHTS OF SERIES 2003-1 CERTIFICATEHOLDERS
                  AND ALLOCATION AND APPLICATION OF COLLECTIONS

     SECTION 4.01 RIGHTS OF THE SERIES 2003-1 CERTIFICATEHOLDERS. The Series
2003-1 Certificates shall represent fractional undivided interests in the Master
Trust, consisting of the right to receive, to the extent necessary to make the
required payments with respect to the Series 2003-1 Certificates at the times
and in the amounts and priorities specified in this Series Supplement,

                                      -18-
<Page>

Collections allocated to Series 2003-1 pursuant to Article IV of the Agreement
and this Article IV, funds on deposit in the Collections Account and the Excess
Funding Account allocable to Series 2003-1 Certificateholders pursuant to
Article IV of the Agreement and this Article IV, and funds on deposit in the
Series 2003-1 Accounts (collectively, the "Series 2003-1 Certificateholders'
Interest"), it being understood that the Series 2003-1 Certificates shall not
represent any interest in any Series Account or Enhancement for the benefit of
any other Series or Class. The Servicer shall apply, or instruct the Master
Trust Trustee to apply, all funds on deposit in the Collections Account and
Excess Funding Account allocable to the Series 2003-1 Certificates, and all
funds on deposit in the Series Principal Account, the Spread Account and the
Distribution Account maintained for the Series 2003-1 Certificateholders, as
described in this Article IV.

     SECTION 4.02 ESTABLISHMENT OF SERIES PRINCIPAL ACCOUNT, SPREAD ACCOUNT,
SERVICER TRANSITION FEE ACCOUNT AND LIQUIDITY RESERVE ACCOUNT.

          (a)  SERIES PRINCIPAL ACCOUNT.

               (i)     On or prior to the commencement of an Early Amortization
     Period or the Accumulation Period, the Master Trust Trustee, for the
     benefit of the Series 2003-1 Certificateholders, shall establish and
     maintain in the name of the Master Trust an Eligible Deposit Account
     bearing a designation clearly indicating that the funds deposited therein
     are held for the benefit of the Series 2003-1 Certificateholders (the
     "Series Principal Account"). The Master Trust Trustee shall possess all
     right, title and interest in all funds on deposit from time to time in the
     Series Principal Account and in all proceeds thereof. Pursuant to authority
     granted to it pursuant to SECTION 3.01(b) of the Agreement, the Servicer
     shall have the revocable power to instruct the Master Trust Trustee to
     withdraw funds from the Series Principal Account for the purpose of
     carrying out the duties of the Servicer under this Series Supplement and
     the Agreement. The Servicer at all times shall maintain accurate records
     reflecting each transaction in the Series Principal Account.

               (ii)    Funds on deposit in the Series Principal Account
     overnight or for a longer period shall at all times be invested in Eligible
     Investments at the direction of the Servicer or its agent, subject to the
     restrictions set forth in the Agreement and subject to the requirement that
     each such Eligible Investment shall have a stated maturity on or prior to
     the following Transfer Date (or such longer maturity as shall be allowed
     upon satisfaction of the Series 2003-1 Rating Agency Condition). Net
     interest and earnings (less investment expenses) on funds on deposit in the
     Series Principal Account, if any, shall be allocated and distributed as
     provided in SECTION 4.04(a).

          (b)  SPREAD ACCOUNT.

               (i)     On or prior to the Closing Date, the Master Trust
     Trustee, for the benefit of the Series 2003-1 Certificateholders, shall
     cause to be established and maintained in the name of the Master Trust, an
     Eligible Deposit Account bearing a designation clearly indicating that the
     funds deposited therein are held for the benefit of the Series 2003-1
     Certificateholders (the "Spread Account"). The Master Trust Trustee shall
     possess all right, title and interest in all funds on deposit from time to
     time in the Spread Account and in all proceeds thereof. Pursuant to
     authority granted to it pursuant to SECTION 3.01(b) of the Agreement, the
     Servicer shall have the revocable power to instruct the Master Trust
     Trustee to withdraw funds from the Spread Account for the purpose of
     carrying out the duties of the

                                      -19-
<Page>

     Servicer under this Series Supplement and the Agreement. The Servicer at
     all times shall maintain accurate records reflecting each transaction in
     the Spread Account. On the Closing Date, the Seller shall deposit into the
     Spread Account an amount equal to the Initial Spread Account Required
     Amount.

               (ii)    Funds on deposit in the Spread Account overnight or for a
     longer period shall at all times be invested in Eligible Investments at the
     direction of the Servicer or its agent, subject to the restrictions set
     forth in the Agreement and subject to the requirement that each such
     Eligible Investment shall have a stated maturity on or prior to the
     following Transfer Date. Net interest and earnings (less investment
     expenses) on funds on deposit in the Spread Account, if any, shall be
     allocated and distributed as provided in SECTION 4.04.

               (iii)   On any Transfer Date on which the amount of funds on
     deposit in the Spread Account is greater than the Projected Spread on such
     Transfer Date, the Servicer shall withdraw the amount of such excess from
     the Spread Account and allocate and pay such excess to the Seller.

               (iv)    Upon the commencement of and during an Early Amortization
     Period, the Master Trust Trustee will deposit all funds in the Spread
     Account into the Liquidity Reserve Account, and no additional funds shall
     be deposited into the Spread Account.

          (c)  LIQUIDITY RESERVE ACCOUNT.

               (i)     The Master Trust Trustee, for the benefit of the Seller,
     shall establish on or prior to the commencement of an Early Amortization
     Period and maintain or cause to be established and maintained in the name
     of the Master Trust Trustee, an Eligible Deposit Account bearing a
     designation clearly indicating that the funds deposited therein are held
     for the benefit of the Seller (the "Liquidity Reserve Account"). The Seller
     shall possess all right, title and interest in all funds on deposit from
     time to time in the Liquidity Reserve Account and in all proceeds thereof;
     PROVIDED, HOWEVER, that no funds on deposit in the Liquidity Reserve
     Account shall be paid to the Seller if such payment would reduce the funds
     in such account below an amount equal to the Available Subordinated Amount.
     Pursuant to authority granted to it pursuant to SECTION 3.01(b) of the
     Agreement, the Servicer shall have the revocable power to instruct the
     Master Trust Trustee to withdraw funds from the Liquidity Reserve Account
     for the purpose of fulfilling the obligations of the Seller under this
     Series Supplement and the Agreement. The Servicer at all times shall
     maintain accurate records reflecting transactions in the Liquidity Reserve
     Account.

               (ii)    Funds on deposit in the Liquidity Reserve Account
     overnight or for a longer period shall at all times be invested in Eligible
     Investments at the direction of the Seller or its agent, subject to the
     restrictions set forth in the Agreement. Any Eligible Investment with a
     stated maturity shall mature on or prior to the following Transfer Date.
     All net interest and earnings (less investment expenses) on funds on
     deposit in the Liquidity Reserve Account, if any, shall be paid to the
     Seller. On any Transfer Date on which the amount on deposit in the
     Liquidity Reserve Account exceeds the Available Subordinated Amount as of
     the end of such Transfer Date, the Servicer shall withdraw the amount of
     such excess from the Liquidity Reserve Account and allocate and pay such
     excess to the Seller.

                                      -20-
<Page>

          (d)  SERVICER TRANSITION FEE ACCOUNT.

               (i)     On or prior to the Closing Date, the Servicer shall
     establish an Eligible Deposit Account in the name of the Master Trust
     Trustee (the "SERVICER TRANSITION FEE ACCOUNT") and deposit $100,000 of
     cash or Eligible Investments therein. In the event on any Business Day, the
     amount on deposit in the Servicer Transition Fee Account shall be less than
     the Servicer Transition Fee Account Required Deposit Amount, NFC, as
     initial Servicer, shall deposit into the Servicer Transition Fee Account
     the amount of such shortfall. Funds deposited in the Servicer Transition
     Fee Account shall, to the extent permitted by applicable laws, rules and
     regulations, be invested at the written direction of the Servicer in
     Eligible Investments. The Servicer shall be entitled to receive all
     investment earnings on the Servicer Transition Fee Account when and as paid
     without any obligation to (a) either the Master Trust Trustee or (b) the
     Investor Certificateholders, in respect thereof. The Servicer will not have
     any obligation to deposit any such amount in any account established
     hereunder. Such amount will be withdrawn from the Servicer Transition Fee
     Account and delivered to the Servicer.

               (ii)    In the event that a Back Up Servicer shall be appointed
     pursuant to SECTION 7.04, the costs and expenses associated with the Back
     Up Servicer mapping NFC's servicing computer systems shall be paid for with
     the funds on deposit in the Servicer Transition Fee Account and, if such
     funds are not sufficient, shall be paid by NFC, as initial Servicer. In
     addition, in the event that a Successor Servicer shall be appointed
     pursuant to SECTION 10.02 of the Agreement, the set up and servicing
     transition fees and costs of the Successor Servicer shall be paid for with
     funds on deposit in the Servicer Transition Fee Account and, if such funds
     are not sufficient, shall be paid by NFC, as initial Servicer. If the
     amount on deposit in the Servicer Transition Fee Account is insufficient to
     cover all of the fees and expenses associated with the transition of the
     servicing functions or such monthly fees and expenses, no Person will be
     obligated to deposit any additional funds into the Servicer Transition Fee
     Account. If the amount on deposit in the Servicer Transition Fee Account on
     any Business Day, after giving effect to all deposits or withdrawals
     therefrom on that date, is greater than the Servicer Transition Fee Account
     Required Deposit Amount on that Business Day, the excess will be withdrawn
     and distributed to Navistar Financial Corporation; PROVIDED, HOWEVER, after
     the appointment of a Successor Servicer and until all series of
     Certificates are no longer Outstanding, no such withdrawals and
     distributions to Navistar Financial Corporation shall be permitted.

               (e)     REPLACEMENT SERIES 2003-1 ACCOUNTS. If, at any time,
     any of the Series 2003-1 Accounts or the Servicer Transition Fee Account
     ceases to be an Eligible Deposit Account, the Master Trust Trustee (or the
     Servicer on its behalf) shall upon the earlier of (a) 30 calendar days, or
     (b) the next Determination Date, establish a new Series 2003-1 Account or
     Servicer Transition Fee Account meeting the conditions specified in
     paragraphs (a), (b), (c) or (d) above, as applicable, as an Eligible
     Deposit Account and shall transfer any cash and/or any investments to such
     new account. Neither the Seller, the Servicer nor any person or entity
     claiming by, through or under the Seller, the Servicer or any

                                      -21-
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     such person or entity shall have any right, title or interest in, or any
     right to withdraw any amount from, any Series 2003-1 Account, except as
     expressly provided herein.

     SECTION 4.03 [Reserved.]

     SECTION 4.04  APPLICATION OF AVAILABLE CERTIFICATEHOLDER INTEREST
COLLECTIONS.

          (a)  APPLICATION OF AVAILABLE CERTIFICATEHOLDER INTEREST COLLECTIONS.
On each Transfer Date related to a Due Period, the Master Trust Trustee, acting
in accordance with instructions from the Servicer, shall apply Available
Certificateholder Interest Collections for such Due Period in the following
amounts and in the following order of priority:

               (i)     INVESTOR SERVICING FEE. An amount equal to the Investor
     Servicing Fee for such Due Period (unless such amount has been netted
     against deposits to the Collections Account or waived) shall be allocated
     and paid to the Servicer.

               (ii)    CLASS A MONTHLY INTEREST. An amount equal to Class A
     Monthly Interest for the related Distribution Period, PLUS any Class A
     Monthly Interest due with respect to any prior Distribution Period but not
     previously distributed to the Class A Certificateholders on a prior
     Distribution Date, PLUS to the extent permitted by law, additional interest
     at the Class A Certificate Rate for such Distribution Period that has
     accrued on Class A Monthly Interest that was due pursuant to this clause
     (ii) but was not previously distributed to the Class A Certificateholders
     on a prior Distribution Date shall be deposited in the Distribution
     Account.

               (iii)   CLASS B MONTHLY INTEREST. An amount equal to Class B
     Monthly Interest for the related Distribution Period, PLUS any Class B
     Monthly Interest due with respect to any prior Distribution Period but not
     previously distributed to the Class B Certificateholders on a prior
     Distribution Date, PLUS to the extent permitted by law, additional interest
     at the Class B Certificate Rate for such Distribution Period that has
     accrued on Class B Monthly Interest that was due pursuant to this clause
     (iii) but was not previously distributed to the Class B Certificateholders
     on a prior Distribution Date shall be deposited in the Distribution
     Account.

               (iv)    INVESTOR DEALER NOTE LOSSES. An amount equal to the
     Investor Dealer Note Losses, if any, for such Due Period shall be treated
     as Investor Principal Collections for such Transfer Date and shall
     reimburse an equal amount of Investor Dealer Note Losses.

               (v)     REIMBURSEMENT OF CLASS A CERTIFICATEHOLDER CHARGE-OFFS.
     An amount equal to the aggregate amount of unreimbursed Class A
     Certificateholder Charge-Offs, if any, for any prior Due Period shall be
     treated as Investor Principal Collections for such Transfer Date and shall
     reimburse an equal amount of Class A Certificateholder Charge-Offs.

               (vi)    REIMBURSEMENT OF CLASS B CERTIFICATEHOLDER CHARGE-OFFS.
     An amount equal to the aggregate amount of unreimbursed Class B
     Certificateholder Charge-Offs, if any, for any prior Due Period shall be
     treated as Investor Principal Collections for such Transfer Date and shall
     reimburse an equal amount of Class B Certificateholder Charge-Offs.

                                      -22-
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               (vii)   SPREAD ACCOUNT  DEPOSIT AMOUNT.  An amount equal to the
     Spread Account Deposit Amount, if any, for such Transfer Date shall be
     deposited into the Spread Account.

               (viii)  DEFERRED INVESTOR SERVICING FEE. An amount equal to the
     aggregate outstanding amounts of the Investor Servicing Fee which have been
     previously waived pursuant to SECTION 3.01 (unless such amounts have been
     waived again) shall be allocated and paid to the Servicer.

               (ix)    REINSTATEMENT OF AVAILABLE SUBORDINATED AMOUNT. An amount
     equal to the excess, if any, of the Maximum Subordinated Amount as of the
     end of the preceding Transfer Date over the Available Subordinated Amount
     as of the end of the preceding Transfer Date shall be (A) during the
     Revolving Period or the Accumulation Period, allocated and paid to the
     Seller or (B) during an Early Amortization Period, deposited in the
     Liquidity Reserve Account, and in either case (A) or (B) the Available
     Subordinated Amount shall be reinstated by the amount of such payment or
     deposit.

               (x)     EXCESS INTEREST  COLLECTIONS.  Any remaining Available
     Certificateholder Interest Collections shall be treated as Excess Interest
     Collections, and applied pursuant to SECTION 4.03(f) of the Agreement.

If Available Certificateholder Interest Collections are not sufficient to
satisfy each of the applications described in clauses (i) through (ix) above on
any Transfer Date, then Excess Interest Collections from other Series allocable
to Series 2003-1 will be applied as Available Certificateholder Interest
Collections in the priority and the manner described in clauses (i) through (ix)
above. If Excess Interest Collections are less than the shortfalls for all
Series that provide for allocations of Excess Interest Collections, such Excess
Interest Collections shall be allocable to shortfalls for Series 2003-1 and any
other Series that so provides PRO RATA based on the relative amounts of each
Series' shortfall.

     SECTION 4.05 APPLICATION OF AVAILABLE SELLER'S FINANCE CHARGE COLLECTIONS,
SPREAD ACCOUNT AND LIQUIDITY RESERVE ACCOUNT TO DEFICIENCY AMOUNT.

          (a)  On each Transfer Date, the Servicer shall determine the amount
(the "Deficiency Amount"), if any, by which the amount of the entire allocations
required on such Transfer Date by SECTIONS 4.04(a)(i) through (vi) exceeds the
amount of Available Certificateholder Interest Collections for such Due Period
and Excess Interest Collections allocated to Series 2003-1 on such Transfer
Date, if any, for the related Due Period.

          (b)  If the Deficiency Amount for any Transfer Date is greater than
zero, the Master Trust Trustee, acting in accordance with instructions from the
Servicer, shall apply available funds from the following sources in the
following order of priority in the same manner as Available Certificateholder
Interest Collections, each of which applications shall reduce such Deficiency
Amount (all such available funds being the "Available Draw Funds" for such
Transfer Date):

               (i)     Available Seller's Finance Charge Collections;

               (ii)    funds on deposit in the Spread Account;

                                      -23-
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               (iii)   for any Transfer Date occurring during any Early
          Amortization Period, funds on deposit in the Liquidity Reserve
          Account;

PROVIDED, HOWEVER, that the amount applied pursuant to this SECTION 4.05(b)
shall not exceed the Draw Amount. The Available Subordinated Amount shall be
reduced by the aggregate amount of Available Draw Funds applied pursuant to this
SECTION 4.05(b).

          (c)  If all of the amounts applied pursuant to SECTION 4.05(a) and (b)
are insufficient to make the entire application described in SECTION
4.04(a)(iv), the Available Subordinated Amount shall be reduced (but not below
zero) by the amount of such deficiency and any remaining Investor Dealer Note
Losses shall be deemed to be reimbursed to the extent of such reduction.

     SECTION 4.06 CERTIFICATEHOLDER CHARGE-OFFS. If, for any Transfer Date on
which the Available Subordinated Amount equals or is reduced to zero (after
giving effect to the allocations, distributions, withdrawals and deposits to be
made on such Transfer Date) and the Deficiency Amount for such Transfer Date (as
reduced by the applications required by SECTION 4.05 of this Series Supplement)
is greater than zero, the Invested Amount shall be reduced by the lesser of (i)
such remaining Deficiency Amount for such Transfer Date and (ii) the amount of
Investor Dealer Note Losses for the related Due Period remaining unreimbursed
after all applications of funds or reductions of the Available Subordinated
Amount pursuant to SECTIONS 4.04 and 4.05 (such lesser amount being a
"Certificateholder Charge-Off"). On any Transfer Date on which Certificateholder
Charge-Offs are greater than zero, such Certificateholder Charge-Offs shall
first reduce the Class B Invested Amount (such amount being a "Class B
Certificateholder Charge-Off") but not below zero; and then reduce the Class A
Invested Amount (such amount being a "Class A Certificateholder Charge-Off") but
not below zero.

     SECTION 4.07 APPLICATION OF SELLER'S FINANCE CHARGE COLLECTIONS.

          (a)  APPLICATION OF AVAILABLE SELLER'S FINANCE CHARGE COLLECTIONS. On
each Transfer Date, the Master Trust Trustee, acting in accordance with
instructions from the Servicer, shall withdraw and apply from the Collections
Account to the extent of Available Seller's Finance Charge Collections for the
related Due Period, the following amounts in the following order of priority:

               (i)     On each Transfer Date related to a Due Period for which a
     Deficiency Amount exists, the amount required by SECTION 4.05(b)(i) shall
     be applied as specified in SECTION 4.05(b).

               (ii)    On each Transfer Date related to a Due Period occurring
     during an Early Amortization Period, the amount, if any, by which the
     Available Subordinated Amount as of the end of such Transfer Date exceeds
     the amount of funds on deposit in the Liquidity Reserve Account shall be
     deposited in the Liquidity Reserve Account.

               (iii)   On each Transfer Date on which the full Spread Account
     Deposit Amount was not deposited in the Spread Account pursuant to SECTION
     4.04(a)(vii), an amount equal to the shortfall in such Spread Account
     Deposit Amount shall be deposited in the Spread Account.

                                      -24-
<Page>

               (iv)    Any remaining Available Seller's Finance Charge
     Collections for the related Due Period shall be allocated and paid to the
     Seller.

          (b)  APPLICATION OF SERIES ALLOCABLE FINANCE CHARGE COLLECTIONS TO THE
SELLER. On each Transfer Date, the Master Trust Trustee, acting in accordance
with instructions from the Servicer, shall withdraw from the Collections Account
and allocate and pay to the Seller an amount equal to the product of (i) the
result of the Excess Seller's Percentage for such Due Period MINUS the Required
Excess Seller Interest Percentage and (ii) Series Allocable Finance Charge
Collections for such Due Period.

     SECTION 4.08 APPLICATION OF SERIES ALLOCABLE PRINCIPAL COLLECTIONS . On
each Business Day, the Master Trust Trustee, acting in accordance with
instructions from the Servicer, shall withdraw Series Allocable Principal
Collections for such Business Day from the Collections Account and apply such
funds in the following amounts:

          (a)  INVESTOR PRINCIPAL COLLECTIONS DURING REVOLVING PERIOD. During
the Revolving Period, an amount equal to Investor Principal Collections for such
Business Day shall be treated as Shared Principal Collections, and applied,
pursuant to the written direction of the Servicer, pursuant to SECTION 4.03(e)
of the Agreement.

          (b)  INVESTOR PRINCIPAL COLLECTIONS DURING ACCUMULATION PERIOD OR
EARLY AMORTIZATION PERIOD. During the Accumulation Period or any Early
Amortization Period, Investor Principal Collections for such Business Day shall
be allocated to the Series 2003-1 Certificateholders and deposited into the
Series Principal Account to the extent the Invested Amount as of the preceding
Distribution Date exceeds the amount of funds on deposit in the Series Principal
Account on such Business Day; PROVIDED, HOWEVER, that for each Business Day of a
Due Period occurring during the Accumulation Period, the amount of Investor
Principal Collections deposited in the Series Principal Account on such Business
Day, when added to the amount of Investor Principal Collections previously
deposited in the Series Principal Account during such Due Period, shall not
exceed the Controlled Deposit Amount for such Due Period. Any Investor Principal
Collections remaining after the applications described in the preceding sentence
shall be treated as Shared Principal Collections, and applied, pursuant to the
written direction of the Servicer, pursuant to SECTION 4.03(e) of the Agreement.

          (c)  SELLER'S PRINCIPAL COLLECTIONS DURING THE REVOLVING PERIOD.
During the Revolving Period, all Seller's Principal Collections for such
Business Day shall be deemed to be Series 2003-1 Shared Seller Principal
Collections and shall be allocated as provided in SECTION 4.08(d)(iii).

          (d)  SELLER'S PRINCIPAL COLLECTIONS DURING ACCUMULATION PERIOD OR
EARLY AMORTIZATION PERIOD; SHARED SELLER PRINCIPAL COLLECTIONS.

               (i)     During the Accumulation Period, Available Seller's
     Principal Collections for such Business Day shall be deemed to be
     "Remaining Available Seller's Principal Collections," which shall be
     included in Series 2003-1 Shared Seller Principal Collections and allocated
     as provided in clause (iii) below. During the Accumulation Period, Excess
     Seller's Principal Collections shall be included in Series 2003-1 Shared
     Seller Principal Collections and allocated as provided in clause (iii)
     below.

                                      -25-
<Page>

               (ii)    During any Early Amortization Period, Available Seller's
     Principal Collections for such Business Day shall be deposited in the
     Liquidity Reserve Account to the extent the Available Subordinated Amount
     as of the end of the immediately preceding Transfer Date exceeds the amount
     of funds on deposit in the Liquidity Reserve Account (including amounts
     deposited pursuant to SECTION 4.07(a)(ii)). The amount required to be
     deposited pursuant to the preceding sentence shall be reduced by the amount
     of Available Seller's Finance Charge Collections deposited in the Liquidity
     Reserve Account on such Business Day. Any remaining Available Seller's
     Principal Collections for such Business Day shall be deemed to be
     "Remaining Available Seller's Principal Collections." During any Early
     Amortization Period, all Excess Seller's Principal Collections, all
     Remaining Available Seller's Principal Collections and all shared seller
     principal collections of any other Series that provides for shared seller
     principal collections not allocated in respect of principal shortfalls
     shall be allocated and paid to the Seller or deposited in the Excess
     Funding Account to the extent necessary to maintain the Master Trust
     Seller's Interest at an amount equal to (or, in the Seller's discretion,
     greater than) the Minimum Master Trust Seller's Interest.

               (iii)   During the Revolving Period or the Accumulation Period,
     Series 2003-1 Shared Seller Principal Collections, if any, and shared
     seller principal collections for any other Series that provides for shared
     seller principal collections shall be determined on each business day and
     allocated in the following priority: (i) to the 2003-1 Series to the extent
     of any Series 2003-1 Accumulation Period Principal Shortfall and to any
     other Series to the extent such Series provides for the use of shared
     seller principal collections in respect of principal shortfalls, (ii) to
     the Excess Funding Account to the extent necessary to maintain the Master
     Trust Seller's Interest at an amount equal to (or, in the discretion of the
     Seller, greater than) the Minimum Master Trust Seller's Interest, (iii) in
     the discretion of the Seller, to make payments on the principal balance of
     any variable funding certificates, and (iv) to the Seller or the holders of
     the Seller's Certificates. If shared seller principal collections for all
     Series, including Series 2003-1 Shared Seller Principal Collections, are
     less than the shortfalls for which shared seller principal collections may
     be used, including any Series 2003-1 Accumulation Period Principal
     Shortfall, then such shared seller principal collections will be allocated
     to all such shortfalls, including any Series 2003-1 Accumulation Period
     Principal Shortfall, PRO RATA based on the relative amounts of each such
     shortfall.

               (iv)    "Series 2003-1 Shared Seller Principal Collections" means
     on each business day (i) during a Revolving Period, all Available Seller's
     Principal Collections and all Excess Seller's Principal Collections and
     (ii) during an Accumulation Period, all Remaining Available Seller's
     Principal Collections and all Excess Seller's Principal Collections. There
     shall be no Series 2003-1 Shared Seller Principal Collections during any
     Early Amortization Period.

          (e)  If on any Distribution Date during an Early Amortization Period
after the application of all funds to be allocated or distributed on such date
the excess, if any, of (x) the Invested Amount over (y) the amount in the Series
Principal Account (the "Early Amortization Period Shortfall Amount") is less
than or equal to the aggregate amount of funds contained in the Liquidity
Reserve Account then funds shall be withdrawn in an amount equal to the Early
Amortization Period Shortfall Amount and shall be deposited in the Series
Principal Account.

                                      -26-
<Page>

     SECTION 4.09  SHARED PRINCIPAL COLLECTIONS.

          (a)  That portion of Shared Principal Collections for any Business Day
equal to the amount of Series 2003-1 Shared Principal Collections for such
Business Day will be allocated in the following priority: (i) to Series 2003-1
and applied in the same manner as Investor Principal Collections pursuant to
SECTION 4.08(b), (ii) deposited in the Excess Funding Account to the extent
necessary to maintain the Master Trust Seller's Interest at an amount equal to
(or, in the discretion of the Seller, greater than) the Minimum Master Trust
Seller's Interest, (iii) in the discretion of the Seller, paid on the principal
balance of any variable funding certificate or (iv) allocated to the Seller.

          (b)  "Series 2003-1 Shared Principal Collections," with respect to any
Business Day, shall mean an amount equal to the Series 2003-1 Principal
Shortfall for such Business Day; PROVIDED, HOWEVER, that, if the aggregate
amount of Shared Principal Collections for all Series for such Business Day is
less than the aggregate amount of Principal Shortfalls for all Series for such
Business Day, then Series 2003-1 Shared Principal Collections for such Business
Day shall equal the product of (x) Shared Principal Collections for all Series
for such Business Day and (y) a fraction, the numerator of which is the Series
2003-1 Principal Shortfall for such Business Day and denominator of which is the
aggregate amount of Principal Shortfalls for all Series for such Business Day.

     SECTION 4.10 DISTRIBUTIONS TO SERIES 2003-1 CERTIFICATEHOLDERS . On each
Transfer Date, after all allocations to the Distribution Account and the Series
Principal Account for the related Transfer Date have been made, the Master Trust
Trustee, acting in accordance with instructions from the Servicer, shall
transfer to the Distribution Account the funds on deposit in the Series
Principal Account and on each Distribution Date shall make, without duplication,
the following distributions from the Distribution Account:

          (a)  INTEREST DISTRIBUTIONS. On each Distribution Date (including the
Expected Principal Payment Date) FIRST, Class A Monthly Interest will be
distributed to the Class A Certificateholders as accrued interest on the Class A
Certificates, and SECOND, Class B Monthly Interest will be distributed to the
Class B Certificateholders as accrued interest on the Class B Certificates. To
the extent any interest is due but not distributed on any such Distribution
Date, such amount will be distributed on the following Distribution Date, along
with, to the extent permitted by law, interest at the applicable Certificate
Rate on such amount.

          (b)  EXPECTED PRINCIPAL PAYMENT DATE. On the Expected Principal
Payment Date, in addition to the amount described in (a) above, amounts on
deposit in the Series Principal Account will be distributed as principal (up to
a maximum of the Invested Amount on such Distribution Date) FIRST, to the Class
A Certificateholders (up to a maximum of the Class A Invested Amount on such
Distribution Date), and SECOND, to the Class B Certificateholders (up to a
maximum of the Class B Invested Amount on such Distribution Date).

          (c)  EARLY AMORTIZATION PERIOD. On each Distribution Date related to a
Due Period occurring during an Early Amortization Period, in addition to the
amount described in (a) above, amounts on deposit in the Series Principal
Account will be distributed as principal FIRST, to the Class A
Certificateholders (up to a maximum of the Class A Invested Amount on such
Distribution Date), and SECOND, to the Class B Certificateholders (up to a
maximum of the Class B Invested Amount on such Distribution Date). Upon the
occurrence of an Early Amortization Event described

                                      -27-
<Page>

in clause SECTION 6.01(b), the distributions described in this SECTION 4.10(c)
will begin on the first Distribution Date occurring after the occurrence of such
Early Amortization Event.

     SECTION 4.11 ACCUMULATION PERIOD LENGTH; ACCUMULATION PERIOD COMMENCEMENT
DATE.. On or prior to the Distribution Date which is ten months prior to the
Distribution Date which is the Expected Principal Payment Date, the Servicer
shall determine in its sole discretion the Accumulation Period Length and the
Accumulation Period Commencement Date and, promptly following such
determination, the Servicer shall notify the Master Trust Trustee and the Rating
Agencies in writing of such determination.

     SECTION 4.12 PARTIAL MONTH DUE PERIOD. The allocation and distribution
provisions in this Series Supplement are based upon the assumptions that each
Due Period will be a calendar month and that each Due Period will have a unique
related Transfer Date and Distribution Date. However, under certain
circumstances (such as the occurrence of an Early Amortization Event, the
Revolving Period could end on a date other than the last day of a calendar month
(the period from the first day of such month (the "Subject Month") to and
including the date of such occurrence being referred to herein as the "Revolving
Due Period"), and an Early Amortization Period could commence on a date other
than the first day of a calendar month (the period from such other date until
the last day of the Subject Month being the "Amortizing Due Period"). If such a
circumstance occurs, then the Servicer, the Seller and the Master Trust Trustee
shall observe the following rules:

               (i)     the Transfer Date for both the Revolving Due Period and
     the Amortizing Due Period shall be the date on which the Transfer Date
     would have occurred if the Subject Month had been an ordinary Due Period;

               (ii)    the allocations and distributions of Finance Charge
     Collections (and all items derived from Finance Charge Collections, such as
     Available Certificateholder Interest Collections and Available Seller's
     Finance Charge Collections) and Dealer Note Losses occurring during the
     Subject Month shall be made as if the Subject Month were one Due Period,
     without any distinction between the Revolving Due Period and the Amortizing
     Due Period; and

               (iii)   two separate sets of allocations and distributions of
     Principal Collections (and all items derived from Principal Collections,
     such as Investor Principal Collections and Seller's Principal Collections)
     shall be made on such Transfer Date, according to whether such Principal
     Collections were received during the Revolving Due Period (in which case
     allocations and distributions shall be made as provided in SECTIONS 4.08(a)
     and (c)) or the Amortizing Due Period (in which case allocations and
     distributions shall be made as provided in SECTIONS 4.08(b) and (d)).

     SECTION 4.13 ADDITIONAL RIGHTS UPON THE OCCURRENCE OF CERTAIN EVENTS.
Notwithstanding the provisions of SECTION 9.02(a) of the Agreement, if any
insolvency event occurs with respect to the Seller, Navistar International
Corporation, International Truck and Engine Corporation or Navistar Financial
Corporation, on the day of such insolvency event, the Seller will (subject to
the actions of the Certificateholders) immediately cease to transfer Dealer
Notes to the Master Trust, and promptly give notice to the Master Trust Trustee
of such insolvency event. Under the terms of the Agreement, if an insolvency
event occurs with respect to the Seller prior to the date on which the Series
2003-1 Certificates issued by the Master Trust have been paid in full, then
within 15 days the Master Trust Trustee will publish a notice of such insolvency
event stating that the Master Trust Trustee intends to

                                      -28-
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sell, liquidate or otherwise dispose of the Dealer Notes in a commercially
reasonable manner and on commercially reasonable terms, unless within a
specified period of time Certificateholders representing more than 50% of the
aggregate series invested amount of the senior most outstanding Class of
Investor Certificates of each such Series and each person holding a Supplemental
Certificate, instruct the Master Trust Trustee not to sell, dispose of or
otherwise liquidate the Dealer Notes and to continue transferring Dealer Notes
as before such insolvency event.

                                    ARTICLE V
                            DISTRIBUTIONS AND REPORTS
                       TO SERIES 2003-1 CERTIFICATEHOLDERS

     SECTION 5.01  DISTRIBUTIONS.

          (a)  The Paying Agent shall distribute (in accordance with the Monthly
Servicer Certificate and Settlement Statement delivered by the Servicer to the
Master Trust Trustee and the Paying Agent pursuant to SECTION 3.04(d) of the
Agreement) to each Series 2003-1 Certificateholder of record on the preceding
Record Date (other than as provided in SECTION 12.02 of the Agreement respecting
a final distribution) on each Distribution Date such Certificateholder's PRO
RATA share (based on the aggregate fractional undivided interests represented by
the Series 2003-1 Certificates held by such Certificateholder) of the amounts on
deposit in the Series 2003-1 Accounts as is payable to the Series 2003-1
Certificateholders on such Distribution Date pursuant to SECTIONS 4.10(a), (b)
and (c).

          (b)  Except as provided in SECTION 12.03 of the Agreement with respect
to a final distribution, distributions to Series 2003-1 Certificateholders
hereunder shall be made by check mailed to each Series 2003-1 Certificateholder
at such Certificateholder's address appearing in the Certificate Register
without presentation or surrender of any Series 2003-1 Certificate or the making
of any notation thereon; PROVIDED, HOWEVER, that, with respect to Series 2003-1
Certificates registered in the name of a Common Depository, such distributions
shall be made to such Common Depository in immediately available funds.

     SECTION 5.02  MONTHLY AND ANNUAL CERTIFICATEHOLDERS' STATEMENT.

          (a)  MONTHLY SERIES 2003-1 CERTIFICATEHOLDERS' STATEMENT. At least two
Business Days prior to each Distribution Date, the Servicer will provide to the
Master Trust Trustee and the Paying Agent, and on each Distribution Date, the
Paying Agent shall forward to each Series 2003-1 Certificateholder a Monthly
Servicer Certificate and Settlement Statement substantially in the form of
EXHIBIT B with such changes as the Servicer shall deem necessary or appropriate,
prepared by the Servicer and delivered to the Master Trust Trustee setting
forth, among other things, the following information (which, in the case of
(iii), (iv), (v), (viii), (ix) and (xi) below, will be stated on the basis of an
original principal amount of $1,000 per Series 2003-1 Certificate):

               (i)     the aggregate  amount of  Collections,  including the
     aggregate amount of Finance Charge Collections and the aggregate amount of
     Principal Collections for the related Due Period;

               (ii)    the Series 2003-1 Allocation  Percentage,  the Floating
     Allocation Percentage and the Principal Allocation Percentage (if
     applicable) for the related Due Period;

                                      -29-
<Page>

               (iii)   the total amount, if any, to be distributed on each of
     the Class A Certificates and the Class B Certificates on such Distribution
     Date;

               (iv)    the amount, if any, of such distribution allocable to the
     Invested Amount, the Class A Invested Amount and the Class B Invested
     Amount;

               (v)     the amount, if any, of such distribution allocable to
     interest on the Class A Certificates and on the Class B Certificates;

               (vi)    Dealer Note Losses and Investor Dealer Note Losses for
     the related Due Period;

               (vii)   the Draw Amount as of the related Transfer Date, if any;

               (viii)  the amount of Certificateholder Charge-Offs, Class A
     Certificateholder Charge-Offs, Class B Certificateholder Charge-Offs and
     the amount of reimbursement of each as of the related Transfer Date;

               (ix)    the amount of the Investor Servicing Fee to be paid on
     such Distribution Date;

               (x)     the Controlled Deposit Amount for the related Due Period
     (if applicable);

               (xi)    the Invested Amount, the Class A Invested Amount and the
     Class B Invested Amount (after giving effect to all distributions that will
     occur on such Distribution Date);

               (xii)   the aggregate amount of Dealer Notes and funds on deposit
     in each of the Excess Funding Account, Series Principal Account, Spread
     Account and the Servicer Transition Fee Account as of the end of the last
     day of the related Due Period (after giving effect to payments and
     adjustments made pursuant to Article IV of this Series Supplement and of
     the Agreement);

               (xiii)  the Available Subordinated Amount (after giving effect to
     draws thereon) as of the end of the related Transfer Date;

               (xiv)   with respect to Eligible Investments in the Series
     Principal Account, the Excess Funding Account, the Liquidity Reserve
     Account and the Servicer Transition Fee Account, as of the last day of the
     related Due Period, the aggregate amount of funds invested in Eligible
     Investments in each such account, a brief description of each such Eligible
     Investment and amount invested in each such Eligible Investment, the rate
     of interest applicable to each such Eligible Investment and the rating of
     each such Eligible Investment;

               (xv)    the Dealers with the five largest aggregate  outstanding
     principal amounts of Dealer Notes in the Master Trust as of the end of the
     related Due Period;

               (xvi)   the  aggregate  outstanding  principal  amount of Dealer
     Notes issued to finance each of OEM Vehicles and used vehicles as of the
     end of the related Due Period;

                                      -30-
<Page>

               (xvii)  the percentages and all other information calculated
     pursuant to SECTION 6.01 to determine whether an Early Amortization Event
     has occurred;

               (xviii) the amount of Excess Interest Collections and Investor
     Principal Collections treated as Shared Principal Collections, each for the
     related Due Period, and the amount of such Excess Interest Collections and
     Shared Principal Collections allocated to other Series; and

               (xix)   the amount of Remaining Available Seller's Principal
     Collections, the amount of Excess Seller's Principal Collections and
     Remaining Available Seller's Principal Collections treated as Series 2003-1
     Shared Seller Principal Collections, the amount of Shared Seller Principal
     Collections from other Series, and the amount of Shared Seller Principal
     Collections allocated to Series 2003-1 and to other Series, each for the
     related Due Period.

          (b)  A copy of the statement provided pursuant to subsection (a) will
be made available for inspection at the Corporate Trust Office.

          (c)  ANNUAL CERTIFICATEHOLDER'S TAX STATEMENT. On or about January 31
of each calendar year, beginning with calendar year 2004, the Master Trust
Trustee shall furnish to the Servicer and Paying Agent a list of each Person who
at any time during the preceding calendar year was a Series 2003-1
Certificateholder and received any payment thereon and the dates such Person
held a Series 2003-1 Certificate, and the Paying Agent shall furnish to each
such Series 2003-1 Certificateholder a statement prepared by the Paying Agent
containing the information prepared by the Master Trust Trustee which is
required to be contained in the statement to Series 2003-1 Certificateholders as
set forth in SECTIONS 5.02(a)(iii)-(a)(v) above, aggregated for such calendar
year or the applicable portion thereof during which such Person was a Series
2003-1 Certificateholder, together with such other customary information as the
Master Trust Trustee or the Servicer deems necessary or desirable to enable the
Series 2003-1 Certificateholders to prepare their tax returns, including
information (to be supplied by the Servicer to the Master Trust Trustee)
regarding original issue discount on the Series 2003-1 Certificates, if any.
Such obligation of the Paying Agent shall be deemed to have been satisfied to
the extent that substantially comparable information shall be provided by the
Master Trust Trustee pursuant to any requirements of the Internal Revenue Code
as from time to time in effect.

                                   ARTICLE VI
                            EARLY AMORTIZATION EVENTS

     SECTION 6.01 ADDITIONAL EARLY AMORTIZATION EVENTS. The occurrence of any of
the following events shall, immediately upon the occurrence thereof without
notice or other action on the part of the Master Trust Trustee or the Series
2003-1 Certificateholders, be deemed to be an Early Amortization Event solely
with respect to Series 2003-1:

          (a)  the Invested Amount is not reduced to zero by the Expected
Principal Payment Date;

          (b)  the United States government or any agency or instrumentality
thereof files a notice of a lien under Internal Revenue Code Section 6323 or any
similar statutory provision (including, but not limited to, Section 302(f) or
Section 4068 of ERISA) on the assets of NFC or NFSC which is or may in the

                                      -31-
<Page>

future be prior to the lien of the Master Trust Trustee or the assets of the
Master Trust (including, without limitation, proceeds of the Dealer Notes);

          (c)  failure on the part of the Seller (i) to make any payment,
distribution or deposit required under the Agreement within five business days
of the date required or (ii) to observe or perform in any material respect any
other material covenants or agreements of the Seller, which continues unremedied
for a period of 60 days after written notice of such failure shall have been
given to the Seller;

          (d)  any representation or warranty made by the Seller pursuant to the
Agreement or any information contained in the schedule of Dealer Notes delivered
thereunder or this Series Supplement shall prove to have been incorrect in any
material respect when made or when delivered, which representation, warranty or
schedule, or the circumstances or condition that caused such representation,
warranty or schedule to be incorrect, continues to be incorrect or uncured in
any material respect for a period of 60 days after written notice of such
incorrectness shall have been given to the Seller and as a result of which the
interests of the Series 2003-1 Certificateholders are materially and adversely
affected, except that an Early Amortization Event shall not be deemed to occur
if the Seller has repurchased the related Dealer Notes or all such Dealer Notes,
if applicable, during such period in accordance with the provisions of the
Agreement;

          (e)  the Seller shall become legally unable for any reason to transfer
Dealer Notes to the Master Trust in accordance with the provisions of the
Agreement;

          (f)  on any Transfer Date, the Available Subordinated Amount for such
 Transfer Date will be reduced to an amount less than the Required Subordinated
 Amount;

          (g)  any Servicer Termination Event shall occur (i) which would have a
material adverse effect on the Series 2003-1 Certificateholders and (ii) for
which the Servicer has received a notice of termination;

          (h)  the delivery by the Seller to the Master Trust Trustee of a
notice stating that the Seller will no longer continue to sell Dealer Notes to
the Master Trust commencing on the date specified in such notice;

          (i)  the Average Coverage Differential shall be equal to or less than
 negative two percent (-2.00%) on each of three consecutive Determination Dates;

          (j)  at the end of any Due Period, the Master Trust Seller's Interest
is reduced to an amount less than the Master Trust Minimum Seller's Interest and
the Seller has failed to assign additional Dealer Notes to the Master Trust in
the amount of such deficiency within ten Business Days following the end of such
Due Period;

          (k)  on any Determination Date, the quotient of (i) the product of (a)
the sum of Dealer Note Collections for each of the related Due Period and the
two immediately preceding Due Periods and (b) four DIVIDED BY (ii) the daily
average principal amount of Dealer Notes outstanding during such Due Periods
("Turnover") is less than 1.7;

          (l)  on any Determination Date, the quotient of (i) the sum of Dealer
Note Losses for each of the related Due Period and the five immediately
preceding Due Periods and (ii) the sum

                                      -32-
<Page>

of Principal Collections for each of the related Due Period and the five
immediately preceding Due Periods, is greater than or equal to one percent
(1.00%);

          (m)  any of the Seller, ITEC, NIC or NFC shall file a petition
commencing a voluntary case under any chapter of the federal bankruptcy laws; or
the Seller or NFC shall file a petition or answer or consent seeking
reorganization, arrangement, adjustment or composition under any other similar
applicable federal law, or shall consent to the filing of any such petition,
answer or consent; or the Seller, ITEC, NIC or NFC shall appoint, or consent to
the appointment of a custodian, receiver, liquidator, trustee, assignee,
sequestrator or other similar official in bankruptcy or insolvency of it or of
any substantial part of its property; or the Seller, ITEC, NIC or NFC shall make
an assignment for the benefit of creditors, or shall admit in writing its
inability to pay its debts generally as they become due;

          (n)  any order for relief against any of the Seller, ITEC, NIC or NFC
shall have been entered by a court having jurisdiction in the premises under any
chapter of the federal bankruptcy laws, and such order shall have continued
undischarged or unstayed for a period of 120 days; or a decree or order by a
court having jurisdiction in the premises shall have been entered approving as
properly filed a petition seeking reorganization, arrangement, adjustment, or
composition of the Seller, ITEC, NIC or NFC under any other similar applicable
federal law, and such decree or order shall have continued undischarged or
unstayed for a period of 120 days; or a decree or order of a court having
jurisdiction in the premises for the appointment of a custodian, receiver,
liquidator, trustee, assignee, sequestrator or other similar official in
bankruptcy or insolvency of the Seller, ITEC, NIC or NFC of any substantial part
of their property, or for the winding up or liquidation of their affairs, shall
have been entered, and such decree or order shall have remained in force
undischarged or unstayed for a period of 120 days;

          (o)  failure on the part of ITEC to make a deposit in the Interest
Deposit Account required by the terms of the Interest Deposit Agreement on or
before the date occurring five Business Days after the date such deposit is
required by the Interest Deposit Agreement to be made; and

          (p)  on any Distribution Date, as of the last day of the related Due
Period, the aggregate principal balance of Dealer Notes owned by the Master
Trust which were advanced against financed vehicles which are used vehicles
exceeds 25% of the aggregate principal balance of all Dealer Notes owned by the
Master Trust.

                                      -33-
<Page>

                                   ARTICLE VII
                             OTHER SERIES PROVISIONS

     SECTION 7.01 CONVEYANCE OF DEALER NOTES. Upon the date on which each
Series is either no longer outstanding or the fully funded date has occurred
with respect thereto, the Master Trust Trustee shall sell, assign and convey to
the Seller or its designee, without recourse, representations or warranty, all
right, title and interest of the Master Trust in the Dealer Notes, whether then
existing or thereafter created, all security interests in the Financed Vehicles
with respect thereto, all monies due or to become due and all amounts received
with respect thereto and all proceeds thereof except for amounts on deposit in
the Collections Account that are allocable to Investor Certificates and amounts
on deposit in any Series Account. The Master Trust Trustee shall execute and
deliver such instruments of transfer and assignment, in each case without
recourse, as shall be reasonably requested by the Seller to vest in the Seller
or its designee all right, title and interest which the Master Trust had in all
such property.

     SECTION 7.02 TAX TREATMENT. The Seller has entered into the Agreement and
this Series Supplement and the Series 2003-1 Certificates have been issued with
the intention that the Series 2003-1 Certificates will qualify under applicable
tax law as indebtedness secured by the Master Trust assets attributable to the
Series 2003-1 Certificates. The Seller and each Series 2003-1 Certificateholder
and Certificate Owner, by the acceptance of its Series 2003-1 Certificate or
Book-Entry Certificate, as applicable, agrees to treat the Series 2003-1
Certificates as indebtedness secured by the Master Trust assets attributable to
the Series 2003-1 Certificates, for Federal income taxes, state and local income
and franchise taxes and any other taxes imposed on or measured by income in
whole or in part.

     SECTION 7.03 BACK UP SERVICER TRIGGER EVENTS. The occurrence of any of the
following events shall be deemed to be an Back Up Servicer Trigger Event:

          (a)  any failure by the Servicer to make any payment, transfer or
deposit or to give instructions to the Master Trust Trustee to make any such
payment, transfer or deposit or to give notice to the Master Trust Trustee as to
any action taken under any Enhancement Agreement on or before the date occurring
five Business Days after the date such payment, transfer or deposit is required
to be made or given, as the case may be, under the terms of the Agreement;

          (b)  failure on the part of the Servicer duly to observe or perform in
any material respect any other covenants or material agreements of the Servicer
set forth in the Agreement, which continues unremedied for a period of 30 days
after the date on which written notice of such failure, requiring the same to be
remedied, shall have been given to the Servicer by the Master Trust Trustee;

          (c)  any representation, warranty or certification made by the
Servicer in the Agreement or in any certificate delivered pursuant to the
Agreement shall prove to have been incorrect when made, which has a material
adverse effect on the rights of the Holders of the Investor Certificates and
which representation, warranty or certification, or the circumstances or
condition which caused such representation, warranty or certification to be
incorrect, continues to be incorrect or uncured in any material respect for a
period of 30 days after the date on which

                                      -34-
<Page>

written notice of such failure, requiring the same to be remedied, shall have
been given to the Servicer by the Master Trust Trustee;

          (d)  the Servicer shall file a petition commencing a voluntary case
under any chapter of the Federal bankruptcy laws; or the Servicer shall file a
petition or answer or consent seeking reorganization, arrangement, adjustment,
or composition under any other similar applicable Federal law, or shall consent
to the filing of any such petition, answer, or consent; or the Servicer shall
appoint, or consent to the appointment of a custodian, receiver, liquidator,
trustee, assignee, sequestrator or other similar official in bankruptcy or
insolvency of it or of any substantial part of its property; or the Servicer
shall make an assignment for the benefit of creditors, or shall admit in writing
its inability to pay its debts generally as they become due; or

          (e)  any order for relief against the Servicer shall have been entered
by a court having jurisdiction in the premises under any chapter of the federal
bankruptcy laws, and such order shall have continued undischarged or unstayed
for a period of 30 days; or a decree or order by a court having jurisdiction in
the premises shall have been entered approving as properly filed a petition
seeking reorganization, arrangement, adjustment, or composition of the Servicer
under any other similar applicable federal law, and such decree or order shall
have continued undischarged or unstayed for a period of 30 days; or a decree or
order of a court having jurisdiction in the premises for the appointment of a
custodian, receiver, liquidator, trustee, assignee, sequestrator, or other
similar official in bankruptcy or insolvency of the Servicer or of any
substantial part of its property, or for the winding up or liquidation of its
affairs, shall have been entered, and such decree or order shall have remained
in force undischarged or unstayed for a period of 30 days.

          Notwithstanding the foregoing, a delay in or failure of performance
under SECTION 7.03(a) for a period of 10 days or under SECTION 7.03(b) OR (c)
for a period of 60 Business Days, shall not constitute a Backup Servicer Trigger
Event if such delay or failure could not be prevented by the exercise of
reasonable diligence by the Servicer and such delay or failure was caused by an
act of God or the public enemy, acts of declared or undeclared war, public
disorder, rebellion or sabotage, epidemics, landslides, lightning, fire,
hurricanes, earthquakes, floods or similar causes. The preceding sentence shall
not relieve the Servicer from using its best efforts to perform its respective
obligations in a timely manner in accordance with the terms of the Agreement and
the Servicer shall provide the Master Trust Trustee, the Seller and the
Certificateholders with an Officer's Certificate giving prompt notice of such
failure or delay by it, together with a description of its efforts so to perform
its obligations.

     SECTION 7.04 BACK UP SERVICER. (i) Within 120 days after the Closing Date,
and thereafter annually, no later than the date on which it delivers the reports
specified in SECTION 3.06 of the Agreement beginning in April 2005, NFC, as
Servicer, shall deliver to the Master Trust Trustee and each of the Rating
Agencies a list of not less than two potential servicers, each of which shall
meet the criteria specified for a Successor Servicer set forth in SECTION 10.02
of the Agreement. Such list shall include an estimate from each such potential
servicer of (A) its fees and expenses for becoming a back up servicer, at which
time its sole obligation will be to perform systems data mapping of NFC's
servicing computer systems with respect to the Dealer Notes (a "BACK UP
SERVICEr"), (B) its one-time set up servicing transition fees and costs for
assuming the role of Successor Servicer under the Agreement, and (C) its monthly
fees and

                                      -35-
<Page>

expenses for performing the functions of a Successor Servicer (including
physical inventory checks of Dealers).

          (ii) As soon as reasonably practicable after the occurrence of a Back
Up Servicer Trigger Event, the Master Trust Trustee shall retain a third-party
Back Up Servicer from the list of potential servicers most recently delivered by
the Servicer to the Master Trust Trustee who meets the criteria specified for a
Successor Servicer as set forth in SECTION 10.02 of the Agreement and who agrees
to become a Successor Servicer if appointed by the Master Trust Trustee pursuant
to SECTION 10.02 of the Agreement or, if the potential servicers on such list do
not meet the eligibility criteria or are unwilling be become the Successor
Servicer, such other Person who meets those requirements. Unless and until a
Servicer Termination Event occurs and the Back Up Servicer is appointed as the
Successor Servicer, the sole obligation of the Back Up Servicer will be to
perform systems data mapping of NFC's servicing computer systems.

                                  ARTICLE VIII
                               FINAL DISTRIBUTIONS

     SECTION 8.01 SALE OF INVESTORS' INTEREST PURSUANT TO SECTION 2.07 OF THE
AGREEMENT; DISTRIBUTIONS PURSUANT TO SECTION 2.03 OR 12.03 OF THE AGREEMENT.

          (a)  The amount to be paid by the Seller to the Collections Account
with respect to Series 2003-1 in connection with a purchase of the
Certificateholders' Interest pursuant to SECTION 2.07 of the Agreement shall
equal the Reassignment Amount for the Distribution Date on which such purchase
occurs.

          (b)  With respect to the Reassignment Amount, if any, deposited into
the Collections Account pursuant to this SECTION 8.01 of this Series Supplement
or SECTION 2.07 of the Agreement or any proceeds deposited into the Collections
Account pursuant to SECTION 12.03(c) of the Agreement, the Master Trust Trustee
shall, not later than 12:00 noon, New York City time, on the Distribution Date
on which such amounts are deposited (or, if such date is not a Distribution
Date, on the immediately following Distribution Date) (in the priority set forth
below): (i) FIRST, deposit the Invested Amount on such Distribution Date into
the Series Principal Account, (ii) SECOND, deposit the amount of accrued and
unpaid interest on the unpaid balance of the Series 2003-1 Certificates in the
Distribution Account, and (iii) THIRD, pay the remainder of any such
Reassignment Amounts to the Seller.

          (c)  Notwithstanding any other provision to the contrary in this
Series Supplement or the Agreement, the entire amount deposited in the Series
Principal Account on a Distribution Date pursuant to SECTION 8.01(b) and all
other amounts on deposit therein shall be distributed in full to the Series
2003-1 Certificateholders on such Distribution Date and any distribution made
pursuant to this paragraph (c) shall be deemed to be a final distribution
pursuant to SECTION 12.03 of the Agreement with respect to Series 2003-1.

     SECTION 8.02 DISTRIBUTION OF PROCEEDS OF SALE, DISPOSITION OR LIQUIDATION
OF THE DEALER NOTES PURSUANT TO SECTION 9.02 OF THE AGREEMENT.

          (a)  Not later than 12:00 noon, New York City time, on the
Distribution Date following the date on which the Insolvency Proceeds are
deposited into the Collections Account

                                      -36-
<Page>

pursuant to SECTION 9.02(b) of the Agreement, the Master Trust Trustee shall
first (in each case, after giving effect to any deposits and distributions
otherwise to be made on such Distribution Date) deduct an amount equal to the
Invested Amount on such Distribution Date from the portion of the Insolvency
Proceeds allocated to Series Allocable Principal Collections and deposit such
amount in the Series Principal Account; PROVIDED that the amount of such deposit
shall not exceed the product of (x) the portion of the Insolvency Proceeds
allocated to Series Allocable Principal Collections and (y) 100% MINUS the
Excess Seller's Percentage with respect to the related Due Period. The remainder
of the portion of the Insolvency Proceeds allocated to Series Allocable
Principal Collections shall be allocated to the Master Trust Seller's Interest
and shall be distributed on such Distribution Date to the Seller.

          (b)  Not later than 12:00 noon, New York City time, on such
Distribution Date, the Master Trust Trustee shall (in each case, after giving
effect to any deposits and distributions otherwise to be made on such
Distribution Date) (a) FIRST, deduct an amount equal to the sum of (i) Class A
Monthly Interest for such Distribution Date, (ii) any Class A Monthly Interest
previously due but not distributed on a prior Distribution Date and (iii) to the
extent permitted by law, interest at the Class A Certificate Rate on Class A
Monthly Interest that was due but not previously distributed to the Class A
Certificateholders on a prior Distribution Date, from the portion of the
Insolvency Proceeds allocated to Series Allocable Finance Charge Collections and
deposit such amount in the Distribution Account, and (b) SECOND, deduct an
amount equal to the sum of (i) Class B Monthly Interest for such Distribution
Date, (ii) any Class B Monthly Interest previously due but not distributed on a
prior Distribution Date and (iii) to the extent permitted by law, interest at
the Class B Certificate Rate on Class B Monthly Interest that was due but not
previously distributed to the Class B Certificateholders on a prior Distribution
Date, from the portion of the Insolvency Proceeds allocated to Series Allocable
Finance Charge Collections and deposit such amount in the Distribution Account;
PROVIDED that the sum of such deposits shall not exceed the product of (x) the
portion of the Insolvency Proceeds allocated to Series Allocable Finance Charge
Collections and (y) 100% MINUS the Excess Seller's Percentage with respect to
the related Due Period. The remainder of the portion of the Insolvency Proceeds
allocated to Series Allocable Finance Charge Collections shall be allocated to
the Master Trust Seller's Interest and shall be distributed on such Distribution
Date to the Seller.

          (c)  Notwithstanding anything to the contrary in this Series
Supplement or the Agreement, the entire amount deposited in the Series Principal
Account and the Distribution Account pursuant to this SECTION 8.02 and all other
amounts on deposit therein shall be distributed in full to the Series 2003-1
Certificateholders on the Distribution Date on which funds are deposited
pursuant to this SECTION 8.02 (or, if not so deposited on a Distribution Date,
on the immediately following Distribution Date) and any distribution made
pursuant to this SECTION 8.02 shall be deemed to be a final distribution
pursuant to SECTION 12.03 of the Agreement with respect to Series 2003-1.

                                      -37-
<Page>

                                   ARTICLE IX
                            MISCELLANEOUS PROVISIONS

     SECTION 9.01 RATIFICATION OF AGREEMENT. As supplemented by this Series
Supplement, the Agreement is in all respects ratified and confirmed and the
Agreement as so supplemented by this Series Supplement shall be read, taken and
construed as one and the same instrument.

     SECTION 9.02 COUNTERPARTS. This Series Supplement may be executed in two or
more counterparts (and by different parties on separate counterparts) each of
which shall be an original, but all of which together shall constitute one and
the same instrument.

     SECTION 9.03 GOVERNING LAW. THIS SERIES SUPPLEMENT SHALL BE CONSTRUED, AND
THE OBLIGATIONS, RIGHTS AND REMEDIES OF THE PARTIES HEREUNDER SHALL BE
DETERMINED, IN ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF ILLINOIS,
WITHOUT REFERENCE TO ITS CONFLICT OF LAW PROVISIONS, EXCEPT THAT THE
OBLIGATIONS, RIGHTS AND REMEDIES OF THE MASTER TRUST TRUSTEE SHALL BE DETERMINED
IN ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD TO
CONFLICT OF LAW PROVISIONS.

     SECTION 9.04 TAX DISCLOSURE. Notwithstanding anything in this Series
Supplement or the Agreement to the contrary, each of the undersigned parties
(and each affiliate and person acting on behalf of any such party) agree that
each party (and each employee, representative, and other agent of such party)
may disclose to any and all persons, without limitation of any kind, the tax
treatment and tax structure of the transactions consummated pursuant to this
Series Supplement and the Agreement (the "TRANSACTIONS") and all materials of
any kind (including opinions or other tax analyses) that are provided to such
party or such person relating to such tax treatment and tax structure, except to
the extent necessary to comply with any applicable federal or state securities
laws. This authorization is not intended to permit disclosure of any other
information including (without limitation) (i) any portion of any materials to
the extent not related to the tax treatment or tax structure of the
Transactions, (ii) the identities of participants or potential participants in
the Transactions, (iii) the existence or status of any negotiations related to
the Transactions, (iv) any pricing or financial information (except to the
extent such pricing or financial information is related to the tax treatment or
tax structure of the Transactions), or (v) any other term or detail not relevant
to the tax treatment or the tax structure of the Transactions.

     SECTION 9.05 CONSENT TO AMENDMENT.

          By the acceptance of any Series 2003-1 Certificate, each Series 2003-1
Certificateholder hereby consents to amendment of the Agreement as follows:

          The definition of "Dealer Note" in SECTION 1.01 of the Agreement is
hereby deleted in its entirety and replaced with the following:

          "DEALER NOTE" shall mean a promissory note acquired by NFC to finance
(i) an International Vehicle or an OEM Vehicle purchased by a Dealer or (ii) a
used truck, truck body, bus or trailer or a new trailer for which NFC chooses to
provide financing to a Dealer. When used herein, unless the context otherwise
requires, "Dealer Notes" shall refer to those Dealer Notes which are held by the
Master Trust.

                                      -38-
<Page>

          Clause (v) of the definition of "Eligible Dealer Note" in SECTION 1.01
of the Agreement is hereby deleted in its entirety and replaced with the
following:

          (v)  which finances a new class 3 or higher truck, truck body or bus
produced by or for a member of the Navistar Group or an OEM Supplier, a new or
used trailer, or a used class 3 or higher truck, truck body or bus.

          The definition of "International Vehicles" in SECTION 1.01 of the
Agreement is hereby deleted in its entirety and replaced with the following:

          "INTERNATIONAL VEHICLES" shall mean any truck, truck body, bus or
trailer produced by, or for, ITEC or an affiliate of ITEC and sold by ITEC to
Dealers.

          The definition of "OEM Vehicle" in SECTION 1.01 of the Agreement is
hereby deleted in its entirety and replaced with the following:

          "OEM VEHICLES" shall mean a new truck, truck body, bus or trailer
manufactured by, or for, a manufacturer other than ITEC.

Such amendment will be effective upon satisfaction of the Rating Agency
Condition and either retirement or consent of each Outstanding series of
Investor Certificates.

          SECTION 9.06  CLASS B CERTIFICATEHOLDER ERISA REPRESENTATION.

          By acquiring a Class B Certificate, each purchaser and transferee will
be deemed to represent, warrant and covenant that it is not acquiring such Class
B Certificate with the assets of an "employee benefit plan" subject to the
employee retirement income security act of 1974, as amended ("ERISA"), a "plan"
described in section 4975(e)(1) of the Internal Revenue Code of 1986, as amended
(the "Code"), any entity deemed to hold "plan assets" of any of the foregoing by
reason of an employee benefit plan's or other plan's investment in such entity,
or a governmental plan subject to applicable law that is substantially similar
to the fiduciary responsibility provisions of ERISA or section 4975 of the Code.

                                  [END OF PAGE]

                            [SIGNATURE PAGE FOLLOWS]

                                      -39-
<Page>

          IN WITNESS WHEREOF, the Seller, the Servicer and the Master Trust
Trustee have caused this Series Supplement to be duly executed by their
respective officers as of the day and year first above written.

                                 NAVISTAR FINANCIAL SECURITIES CORPORATION
                                  as Seller

                                 By:    /s/ Andrew J. Cederoth
                                     ------------------------------------
                                        Andrew J. Cederoth
                                        Vice President and Treasurer

                                 NAVISTAR FINANCIAL CORPORATION
                                  as Servicer

                                 By:    /s/ Andrew J. Cederoth
                                     ------------------------------------
                                        Andrew J. Cederoth
                                        Vice President and Treasurer

                                 THE BANK OF NEW YORK
                                  as Master Trust Trustee

                                 By:    /s/ Jonathan Farber
                                     ------------------------------------
                                        Jonathan Farber
                                        Assistant Treasurer

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Exhibit 4.6  

 
  AMENDMENT NO. 2
  
    TO
  
    INVERNESS MEDICAL INNOVATIONS, INC.
  
    2001 STOCK OPTION AND INCENTIVE PLAN    
    

        The Inverness Medical Innovations, Inc. 2001 Stock Option and Incentive Plan (the "Plan") is hereby amended by deleting the first sentence of
Section 3(a) of the Plan and replacing it with the following: 

"The
maximum number of shares of Stock reserved and available for issuance under the Plan shall be 5,324,081 shares, subject to adjustment as provided in Section 3(b)." 

Except
as herein amended, the provisions of the Plan shall remain in full force and effect. 

AS
APPROVED BY THE BOARD OF DIRECTORS: March 10, 2003 

AS
APPROVED BY THE STOCKHOLDERS: May 21, 2003 

QuickLinks

AMENDMENT NO. 2 TO INVERNESS MEDICAL INNOVATIONS, INC. 2001 STOCK OPTION AND INCENTIVE PLAN

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