Document:

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                                                                    EXHIBIT 10.5

TRANSITION AUTO FINANCE IV, INC.                                    SUBSCRIPTION
$10,000,000 - 9.0% SECURED PROMISSORY NOTES DUE                        AGREEMENT
                  NOVEMBER 1, 2006

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BY COMPLETING AND EXECUTING THIS PAGE, THE INVESTOR HEREBY (i) ACKNOWLEDGES
READING AND UNDERSTANDING THE MATERIAL ON THE REVERSE SIDE, AND (ii) REPRESENTS,
WARRANTS, ACKNOWLEDGES AND AGREES TO ALL PROVISIONS SET FORTH BELOW AND ON THE
REVERSE SIDE.

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Investment Amount $
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1.       INVESTOR TYPE:  (Check One)

(REFER TO THE SIGNATURE REQUIREMENTS IN SUBSCRIPTION INSTRUCTIONS ON REVERSE
SIDE)

[ ]  Individual                    [ ]  IRA
[ ]  Joint Tenant with right       [ ]  Custodian, Uniform
     of survivorship                    Gift to Minors
[ ]  Trust                         [ ]  Pension or Profit
[ ]  Corporation                   [ ]  Keogh Plan
[ ]  General Partnership           [ ]  Other
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2.  INVESTOR DATA - (Please Print)

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Name of Investor

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Social Security or Tax ID#

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2nd Investor Name

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2nd Investor Social Security #

RESIDENT ADDRESS OF INVESTOR:

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Street (Please do not use a P.O. Box)

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City & State                                                   Zip Code

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Home Phone                                        Business Phone

3. SPECIAL REGISTRATION DIRECTION - Please complete this section if the Note
should be registered in the name of an IRA, trustee or clearing broker (for the
benefit of the investor's account). An authorized representative of the
custodian, trustee or clearing broker must execute to evidence consent (see
instruction 1 on reverse hereof)

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Name of Custodian, Trustee or Clearing Brokerage Firm

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Address

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City & State                                                   Zip Code

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Tax ID #                                              Business Phone

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Signature of Authorized Representative of Custodian, Trustee or Clearing
Brokerage Firm

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Name and Title of Authorized Representative

                                   FOR USE OF
                        TRANSITION AUTO FINANCE IV, INC.

Amount $                           Acceptance Date:
         --------                                   --------

Investor #                         Investor State:
           --------                                ---------

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4. SPECIAL PAYMENT DIRECTIONS: Complete this section to direct payment checks
and Form 1099s to an address other than the residence address given in 2 above.
(Note: If the investment is made through an IRA, trustee or clearing broker,
payments must go to custodian, trustee or clearing broker unless other
authorization is attached hereto):

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Name

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Address

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City & State                                                   Zip Code

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Account No. (for payment to a designated account)

5. INVESTOR SUITABILITY: (Read Carefully and Initial) My income and net worth
meet both the minimum required suitability standards as stated in the
Prospectus, and (if applicable) the higher suitability standards applying to my
state of residence. (By signing, fiduciaries signing for beneficiaries represent
that the beneficiaries meet the applicable suitability standards.) IRA Investors
must initial, not the IRA Trustee.

    Investor's Initials              2nd Investor's Initials
---                              ---

6. SIGNATURES - signature must be identical to name of investor. Investment
advisors may not sign on behalf of the investor.

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Signature of Investor                                             Date

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Print Name

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Signature of Second Investor                                Date

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Print Name

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Home Phone                                        Business Phone

7. REGISTERED REPRESENTATIVE STATEMENT - I, the Registered Representative for
the foregoing investor, hereby represent that:

(1) I have reasonable grounds to believe, on the basis of information obtained
from the investor concerning his age, educational level, knowledge of
investment, investment objectives, other investments, financial situation, needs
and any other information known by me that (a) the investor is or will be in a
financial position appropriate to enable him to realize to a significant extent
the merits and risks described in the Prospectus, (b) the investor has a fair
market net worth sufficient to sustain the risks inherent in this investment,
including loss of investment and lack of liquidity, (c) the investor satisfies
both the minimum required suitability standards stated in the Prospectus and (if
applicable) the higher suitability standards for the investor's state of
residence, and (d) this investment is otherwise suitable for the investor;

(2) I will maintain on file documents indicating that Prospectus has been
delivered to the investor and disclosing the basis upon which the determination
of suitability was reached and have, prior to execution of this Subscription
Agreement, informed the investor of all pertinent facts relating to the
liquidity and marketability of the Notes during the term of the investment; and

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Registered Representative's Signature                 Date

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Print Name                                                          Phone

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Broker/Dealer Firm Name

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Address

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City & State                                                   Zip Code

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                             SUBSCRIPTION AGREEMENT

         The investor(s) signatory hereto ("Subscriber") represents, warrants,
acknowledges and agrees as follows:

         1. Subscriber hereby subscribes for the principal amount of 9.0%
Secured Promissory Notes (the "Note") issued by Transition Auto Finance IV, Inc.
("Issuer"), as specified on the reverse side hereof, encloses and hereby tenders
the amount set forth on the reverse side hereof as full payment for the Note for
which he is subscribing, and hereby agrees, subject to the Issuer's acceptance
of his subscription, to become a Noteholder in an amount equal to the amount
tendered. Subscriber agrees that he may not revoke, cancel, terminate or
withdraw his subscription or his Subscription Agreement without the prior
written consent of the Issuer, and acknowledges that the Issuer may reject his
subscription for any reason whatsoever. The minimum investment is $5,000 (or
$2,000 for individual Retirement Accounts).

         2. Subscriber hereby acknowledges receipt of a copy of the current
Prospectus for Transition Auto Finance IV, Inc. 9.0% Secured Promissory Notes
Due November 1, 2006 ("Prospectus") and understands that the Note being acquired
will be governed by the terms of the Indenture referenced in such Prospectus and
such other documents as may be referenced therein. Subscriber further
understands and agrees that, following Issuer's acceptance of his subscription,
he shall receive a Note that shall evidence his status as a Noteholder of
Issuer, such Note to be in the form specified in the Indenture. The information
set forth on the signature page hereof is true and accurate and Subscriber has
proper authority to execute this Subscription Agreement and make this
Investment.

         3. Subscriber hereby represents that this purchase is made for the
Subscriber's own account and not with a view toward distribution. Subscriber
understands that it is not anticipated that an active market will ever develop
for the Note, and that accordingly it may be impossible for Subscriber to
liquidate his investment in the Note, even in the event of an emergency. Any
transfer of the Note must comply with the requirements of the Prospectus, the
Note and with any additional requirements imposed by laws or by any governmental
authorities.

         4. Subscriber hereby acknowledges that the Escrow Agent's sole role in
the offering described in the Prospectus is that of escrow agent, and that the
Escrow Agent has not reviewed the Prospectus and makes no representations
whatsoever as to the nature of such offering or the compliance of such offering
with any applicable state or federal laws, rules or regulations. Subscriber also
understands that the Issuer (and not the Escrow Agent) will make all
computations regarding the amount of interest (if any) that will be paid to such
Subscriber with respect to his subscription payment.

         5. TAX REPRESENTATIONS: Under penalties of perjury, Subscriber hereby
certifies that (i) the number shown on this form and on the accompanying IRS
Work W-9 is Subscriber's correct taxpayer identification number, and (ii) that
Subscriber is not subject to backup withholding because (A) Subscriber has not
been notified that Subscriber is subject to backup withholding as a result of a
failure to report all interest or dividends or (B) the Internal Revenue Service
has notified Subscriber that Subscriber is no longer subject to backup

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withholding. Under penalties of perjury, unless express written disclosure to
the contrary is delivered to the Issuer together with this form, Subscriber
certifies that Subscriber is not a non-resident alien individual, a foreign
partnership, a foreign corporation, or a foreign estate or trust, which would be
a foreign person within the meaning of Section 1441, 1146 and 7701(a) of the
Internal Revenue Code of 1986, as amended, and that Subscriber will notify the
Issuer before a change in Subscriber's foreign status.

                            SUBSCRIPTION INSTRUCTIONS

         1. Complete all applicable items and sign and date this Subscription
Agreement in the places indicated. Subscribers should use full names (not
initials). If you have previously subscribed for a Note in this offering and
wish to subscribe for an additional Note, please complete the entire
Subscription for the new Note. NO SUBSCRIPTION AGREEMENT WILL BE PROCESSED
UNLESS FULLY COMPLETED AND ACCOMPANIED BY THE APPROPRIATE PAYMENT. Parts 3 and 4
need not be completed unless the investor wishes to provide special payment
delivery instructions (Part 4) or to register his Note in the name of an IRA,
trustee or clearing brokerage firm. A separate IRS Form W-9 must be completed,
executed and submitted by the custodian, trustee or clearing brokerage firm.

         2. Make your subscription check payable to "Great Nation Investment
Corporation" for the amount entered under "Amount Enclosed" in the Subscription
Agreement. Mail or deliver your signed Subscription Agreement and your check to
your Registered Representative.

         3. Registered Representatives: Please forward signed Subscription
Agreements and checks to Great Nation Investment Corporation, 5408 A Bell
Street, Amarillo, Texas 79109, Attention: Mr. Pat Treat.

The following signature and other documentation requirements have been
established for the following forms of ownership of the Notes:

JOINT TENANTS AND TENANTS IN COMMON: The signatures of all joint tenants and
tenants in common investors are required unless a separate document, signed by
all parties and designating one a the agent of the other(s) for purposes of
signing the Subscription Agreement, accompanies the Subscription Agreement.

CORPORATION: The signature(s) of an officer(s) authorized to sign on behalf of
the Corporation is (are) required.

PARTNERSHIP: Specify whether the Subscriber is a general or limited partnership.
If it is a general partnership, the signatures of all partners are required. If
it is a limited partnership, the signatures of all general partners are
required.

TRUST: The Subscription Agreement must be signed by the trustee.

UNIFORM GIFTS TO MINORS ACT: The required signature is that of the custodian,
not of the parent (unless the parent has been designated as the custodian). Only
one child is permitted

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in each investment under the Uniform Gifts to Minors Act. Different requirements
may apply in your state. Please consult your attorney for information regarding
these requirements.

If you have any questions regarding these requirements, please call TRANSITION
AUTO FINANCE IV, INC., at 214-360-9966.

                                       5<PAGE>   1

                                TECO ENERGY, INC.

                                       and

                              THE BANK OF NEW YORK
                                   As Trustee

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

                          FIFTH SUPPLEMENTAL INDENTURE

                         dated as of September 10, 2001

                           Supplementing the Indenture

                           dated as of August 17, 1998

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

                                   Relating to

                              7.20 % Notes Due 2011

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                                TABLE OF CONTENTS

                                                                            PAGE

ARTICLE ONE       DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION     2
   Section 101.   Definitions .............................................   2
   Section 102.   Section References ......................................   2

ARTICLE TWO       AMENDMENT OF THE FOURTH SUPPLEMENTAL INDENTURE ..........   2
   Section 201.   Amendment of Section 203 ................................   2
   Section 202.   Amendment of Exhibit A ..................................   2
   Section 203.   Amendment of Exhibit B ..................................   3

ARTICLE THREE     MISCELLANEOUS ...........................................   3
   Section 301.   Effect On Original Indenture ............................   3
   Section 302.   Counterparts ............................................   3
   Section 303.   Recitals ................................................   3
   Section 304.   Governing Law ...........................................   3

                                      -i-
<PAGE>   3

     This Fifth Supplemental Indenture, dated as of September 10, 2001 between
TECO Energy, Inc., a corporation duly organized and existing under the laws of
the State of Florida (hereinafter called the "COMPANY") and having its principal
office at TECO Plaza, 702 North Franklin Street, Tampa, Florida 33602, and The
Bank of New York, as trustee (hereinafter called the "TRUSTEE") and having its
principal corporate trust office at 101 Barclay Street, 21st Floor West, New
York, New York, 10286.

                                   WITNESSETH:

     WHEREAS, the Company and the Trustee entered into an Indenture, dated as of
August 17, 1998 (the "ORIGINAL INDENTURE"), pursuant to which one or more series
of debt of the Company (the "SECURITIES") may be issued from time to time; and

     WHEREAS, Section 201 of the Original Indenture permits the terms of any
series of Securities to be established in an indenture supplemental to the
Original Indenture; and

     WHEREAS, Section 901(7) of the Original Indenture provides that a
supplemental indenture may be entered into by the Company and the Trustee
without the consent of any Holders of the Securities to establish the form and
terms of the Securities of any series; and

     WHEREAS, the Company and the Trustee have entered into supplemental
indentures, including a Fourth Supplemental Indenture, dated as of April 30,
2001 (the "FOURTH SUPPLEMENTAL INDENTURE"), in order to supplement and amend the
Original Indenture by, among other things, establishing the form and terms of
one series of Securities to be known as the Company's "7.20 % Notes Due 2011"
(the "NOTES") and amending and adding certain provisions thereof for the benefit
of the Holders of the Notes; and

     WHEREAS, the Company has requested the Trustee to join with it in the
execution and delivery of this Fifth Supplemental Indenture to amend the
provisions of the Fourth Supplemental Indenture to correct or supplement certain
provisions therein pursuant to Section 901 of the Original Indenture and in
order to supplement and amend the Original Indenture; and

     WHEREAS, the Company and the Trustee desire to enter into this Fifth
Supplemental Indenture to supplement and amend the Fourth Supplemental Indenture
for the purposes set forth in Sections 201 and 901 of the Original Indenture as
referred to above; and

     WHEREAS, the Company has furnished the Trustee with a Board Resolution
authorizing the execution of this Fifth Supplemental Indenture; and

     WHEREAS, all things necessary to make this Fifth Supplemental Indenture a
valid agreement of the Company and the Trustee and a valid supplement to the
Original Indenture have been done,

          NOW, THEREFORE, THIS FIFTH SUPPLEMENTAL INDENTURE WITNESSETH:

     For and in consideration of the premises and the purchase of the Notes to
be issued under the Fourth Supplemental Indenture as amended hereunder by
holders thereof, the Company and

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the Trustee mutually covenant and agree, for the equal and proportionate benefit
of the respective holders from time to time of the Notes, as follows:

                                  ARTICLE ONE

             DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

     SECTION 101.  DEFINITIONS

     All capitalized terms that are used herein and not otherwise defined herein
shall have the meanings assigned to them in the Original Indenture. The Original
Indenture together with this Fifth Supplemental Indenture are hereinafter
sometimes collectively referred to as the "INDENTURE."

     SECTION 102.  REFERENCES

     Each reference to a particular section set forth in this Fifth Supplemental
Indenture shall, unless the context otherwise requires, refer to this Fifth
Supplemental Indenture.

                                  ARTICLE TWO

                 AMENDMENT OF THE FOURTH SUPPLEMENTAL INDENTURE

     SECTION 201.  AMENDMENT OF SECTION 203

     The first paragraph of Section 203 of the Fourth Supplemental Indenture is
hereby amended and restated to read as follows:

          The initial principal amount of Notes that shall be issued under this
     Fourth Supplemental Indenture shall be $400,000,000. Additional Notes may
     be issued under this Fourth Supplemental in unlimited principal amounts as
     permitted by the Original Indenture. The authorized denominations of Notes
     shall be $1,000 or integral multiples of $1,000 in excess thereof.

     SECTION 202. AMENDMENT OF EXHIBIT A

     The form of Note attached to the Fourth Supplemental Indenture as Exhibit A
is here by amended as follows:

     (a)  The number "$400,000,000" following the words "PRINCIPAL AMOUNT" on
the first page of the Note is replaced with a blank space.

     (b)  The final sentence of the first paragraph on the back of the Note is
hereby amended and restated to read as follows:

     This Note is one of the securities of the series designated on the face
hereof.

                                      -2-
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     SECTION 203.  AMENDMENT OF EXHIBIT B

     The first paragraph of Exhibit B to the Fourth Supplemental Indenture is
hereby amended and restated to read as follows:

          Pursuant to Section 206 of Article Two of the Fourth Supplemental
     Indenture, dated as of April 30, 2001, as amended, to the Indenture, dated
     as of August 17, 1998, as amended, you are instructed to prepare and
     authenticate a Note, of the series identified above, in the principal
     amount of $______________. To the extent not previously delivered, attached
     hereto are any documents required to be delivered pursuant to Section 303
     of the Indenture.

                                 ARTICLE THREE

                                  MISCELLANEOUS

     SECTION 301.  EFFECT ON ORIGINAL INDENTURE

     The Fifth Supplemental Indenture is a supplement to the Original Indenture.
As supplemented by this Fifth Supplemental Indenture, the Original Indenture is
in all respects ratified, approved and confirmed, and the Original Indenture and
this Fifth Supplemental Indenture shall together constitute one and the same
instrument.

     SECTION 302.  COUNTERPARTS

     This Fifth Supplemental Indenture may be executed in any number of
counterparts, each of which so executed shall be deemed to be an original, but
all such counterparts shall together constitute by one and the same instrument.

     SECTION 303.  RECITALS

     The recitals contained herein shall be taken as the statements of the
Company, and the Trustee assumes no responsibility for their correctness. The
Trustee makes no representations as to the validity or sufficiency of this Fifth
Supplemental Indenture.

     SECTION 304.  GOVERNING LAW

     This Fifth Supplemental Indenture shall be governed by and construed in
accordance with the laws of the jurisdiction that govern the Original Indenture
and its construction.

              [The balance of this page intentionally left blank.]

                                      -3-

<PAGE>   6

     IN WITNESS WHEREOF, the parties hereto have caused this Fifth Supplemental
Indenture to be duly executed as of the date and year first written above.

                                       TECO ENERGY, INC.

                                       By: /s/ Gordon L. Gillette
                                          --------------------------------------
                                          Name:  Gordon L. Gillette
                                          Title: Senior Vice President - Finance
                                                 and Chief Financial Officer

                                       THE BANK OF NEW YORK, AS TRUSTEE

                                       By: /s/ Remo J. Reale
                                          --------------------------------------
                                          Name:  Remo J. Reale
                                          Title: Vice President

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