Executed in 6 Parts
                                                          Counterpart No. (   )


                              NATIONAL EQUITY TRUST


                            OTC GROWTH TRUST SERIES 6


                            REFERENCE TRUST AGREEMENT


     This  Reference  Trust  Agreement  dated   ,  2000 among  Prudential
Securities Incorporated, as Depositor and The Bank of New York, as Trustee, sets
forth certain  provisions in full and incorporates other provisions by reference
to the document entitled  "National Equity Trust, Trust Indenture and Agreement"
(the "Basic Agreement") dated February 2, 2000. 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.

<PAGE>
                                     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, OTC Growth Trust Series
        6.

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

     C. The publicly  traded stocks 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 be on such dates as
the Sponsor shall direct.

     I. The term "Distribution Date" shall be on such dates as the Sponsor shall
direct.

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

     K. The Trustee's Annual Fee shall be $ (per 1,000 Units) for 49,999,999 and
below units outstanding $ (per 1,000 Units) on the next 50,000,000 Units, $ (per
1,000 Units) on the next 100,000,000  Units, and $ (per 1,000 Units) on Units in
excess of 200,000,000  Units. In calculating  the Trustee's  annual fee, the fee
applicable  to the  number  of  units  outstanding  shall  apply  to  all  units
outstanding.

     L. The Depositor's  Portfolio  supervisory service fee shall be $ per 1,000
Units.
                  [Signatures and acknowledgments on separate pages]