Executed in 6 Parts
                                                             Counterpart No. ( )


                              NATIONAL EQUITY TRUST

                            LOW FIVE PORTFOLIO SERIES 216

                            REFERENCE TRUST AGREEMENT

     This Reference  Trust Agreement  dated , 2000 among  Prudential  Securities
Incorporated,  as Depositor and The Chase Manhattan Bank, as Trustee, sets forth
certain provisions in full and incorporates other provisions by reference to the
document  entitled  "National  Equity  Trust Low Five  Portfolio  Series,  Trust
Indenture and  Agreement"  (the "Basic  Agreement")  dated April 25, 1995.  Such
provisions  as  are  set  forth  in  full  herein  and  such  provisions  as are
incorporated by reference constitute a single instrument (the "Indenture").

                                WITNESSETH THAT:


     In  consideration  of the  premises  and of the  mutual  agreements  herein
contained, the Depositor and the Trustee agree as follows:

                                     Part I.

                     STANDARD TERMS AND CONDITIONS OF TRUST

     Subject to the provisions of Part II hereof,  all the provisions  contained
in the Basic  Agreement are herein  incorporated  by reference in their entirety
and  shall be deemed  to be a part of this  instrument  as fully and to the same
extent as though said  provisions had been set forth in full in this  instrument
except that the Basic Agreement is hereby amended in the following manner:

     A.   Article I, entitled "Definitions", paragraph 22, shall be amended as
          follows:

               "Trustee  shall mean the Chase  Manhattan  Bank, or any successor
               trustee appointed as hereinafter provided."

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     B.   Article II, entitled "Deposit of Securities; Acceptance of Trust",
          shall be amended as follows:

               The  second  sentence  of Section  2.03  Issue of Units  shall be
               amended by deleting the words "on any day on which the  Depositor
               is the only Unit Holder".

     C.   Article III, entitled "Administration of Trust", shall be amended as
          follows:

          (i)  Section 3.01 Initial Costs shall be amended to substitute the
               following language:

               Section 3.01.  Initial Cost The costs of organizing the Trust and
               sale of the Trust  Units  shall,  to the  extent of the  expenses
               reimbursable  to the Depositor  provided  below,  be borne by the
               Unit Holders, provided,  however, that, to the extent all of such
               costs are not borne by Unit Holders, the amount of such costs not
               borne  by Unit  Holders  shall be  borne  by the  Depositor  and,
               provided further,  however, that the liability on the part of the
               Depositor  under this section shall not include any fees or other
               expenses  incurred in connection with the  administration  of the
               Trust subsequent to the deposit referred to in Section 2.01. Upon
               notification  from the Depositor that the primary offering period
               is  concluded,  the Trustee  shall  withdraw  from the Account or
               Accounts specified in the Prospectus or, if no Account is therein
               specified,  from the Principal Account,  and pay to the Depositor
               the Depositor's reimbursable expenses of organizing the Trust and
               sale of the Trust Units in an amount  certified to the Trustee by
               the  Depositor.  If the  balance  of  the  Principal  Account  is
               insufficient  to make such  withdrawal,  the  Trustee  shall,  as
               directed by the  Depositor,  sell  Securities  identified  by the
               Depositor,  or distribute to the  Depositor  Securities  having a
               value,  as  determined  under  Section  4.01  as of the  date  of
               distribution,    sufficient   for   such    reimbursement.    The
               reimbursement  provided  for in  this  section  shall  be for the
               account of the  Unitholders  of record at the  conclusion  of the
               primary  offering  period  and  shall  not  be  reflected  in the
               computation of the Unit Value prior thereto. As used herein, the

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               Depositor's  reimbursable  expenses of  organizing  the Trust and
               sale of the Trust  Units  shall  include  the cost of the initial
               preparation  and  typesetting  of  the  registration   statement,
               prospectuses (including preliminary prospectuses), the indenture,
               and other documents relating to the Trust, SEC and state blue sky
               registration  fees,  the  cost of the  initial  valuation  of the
               portfolio  and audit of the Trust,  the initial fees and expenses
               of the  Trustee,  and  legal  and  other  out-of-pocket  expenses
               related thereto,  but not including the expenses  incurred in the
               printing of preliminary  prospectuses and prospectuses,  expenses
               incurred in the  preparation  and printing of brochures and other
               advertising  materials and any other selling  expenses.  Any cash
               which  the   Depositor   has   identified   as  to  be  used  for
               reimbursement  of  expenses  pursuant  to this  Section  shall be
               reserved by the Trustee for such purpose and shall not be subject
               to distribution or, unless the Depositor otherwise directs,  used
               for  payment  of  redemptions  in excess of the  per-Unit  amount
               allocable to Units  tendered for  redemption.  As directed by the
               Depositor,  the  Trustee  will  advance  funds to the Trust in an
               amount  necessary to  reimburse  the  Depositor  pursuant to this
               Section and shall  recover such advance from the sale or sales of
               Securities at such time as the Depositor shall direct,  but in no
               event later than the  termination of the Trust.  Repayment of any
               such  advance  shall be  secured  by a lien on the  assets of the
               Trust prior to the  interest  of the Unit  Holders as provided in
               Section 6.04.

          (ii) The third paragraph of Section 3.05 Distribution shall be amended
               to add the following sentence at the end thereof:

               "The  Trustee  shall  make a  special  distribution  of the  cash
               balance in the Income and Principal  accounts  available for such
               distribution  to Unit  Holders  of  record  on such  dates as the
               Depositor   shall  direct,   provided   however,   that  no  such
               distribution  shall be made if the assets of the Trust subsequent
               to such  distribution  would not exceed any Deferred Sales Charge
               payable and other trust expenses."

          (iii) The second to the last paragraph of Section 3.08 Sale of
               Securities shall be amended to replace the word "equal" with the
               following phrase: "be sufficient to pay."


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     D.   Reference to United States Trust Company of New York in its capacity
          as Trustee is replaced by the Chase Manhattan Bank throughout the
          Basic Agreement.

                                       Part II.

                         SPECIAL TERMS AND CONDITIONS OF TRUST


     The following special terms and conditions are hereby agreed to:

                  A.    The Trust is denominated National Equity
            Trust, Low Five Portfolio Series 216.

                  B.    The Units of the Trust shall be subject to
            a deferred sales charge.

                  C. The  contracts  for the  purchase of common stock listed in
            Schedule  A hereto  are those  which,  subject  to the terms of this
            Indenture,  have been or are to be  deposited  in Trust  under  this
            Indenture as of the date hereof.

                  D.    The term "Depositor" shall mean Prudential
            Securities Incorporated.

                  E.    The aggregate number of Units referred to
            in Sections 2.03 and 9.01 of the Basic Agreement is
                     as of the date hereof.

                  F.    A Unit of the Trust is hereby declared
            initially equal to 1/     th of the Trust.

                  G.    The term "First Settlement Date" shall mean
                     , 2000.

                  H.    The terms "Computation Day" and "Record
            Date" shall mean on the tenth day of     2000,     2000,     2000,
            and        2001.

                  I.    The term "Distribution Date" shall be on such mean on
            the twenty-fifth day of       2000,       2000,       2000, and
            2001 or as soon thereafter as possible.

                  J.    The term "Termination Date" shall mean
                     , 2001.

                  K. The  Trustee's  Annual Fee shall be $ (per 1,000 Units) for
            100,000,000 and above units outstanding; $0.80 (per 1,000 Units) for
            50,000,000 - 99,999,999 units  outstanding;  $0.86 (per 1,000 Units)
            for  49,999,999  and below units  outstanding.  In  calculating  the
            Trustee's  annual  fee,  the fee  applicable  to the number of units
            outstanding shall apply to all units outstanding.

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                  L.    The Depositor's Portfolio supervisory
            service fee shall be $0.25 per 1,000 Units.

                  [Signatures and acknowledgments on separate pages]