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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549



                                  SCHEDULE 13G
                                 (Rule 13d-102)

             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
             TO RULES 13d-1(b) AND (c) AND AMENDMENTS THERETO FILED
                              PURSUANT TO 13d-2(b)
                              (Amendment No. 5)(1)


                                IDEX CORPORATION
                                (Name of Issuer)


                     COMMON STOCK, PAR VALUE $.01 PER SHARE
                         (Title of Class of Securities)


                                   45167R-10-4
                                 (CUSIP Number)


(1) The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).



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- ------------------------                                    --------------------
 CUSIP No. 45167R-10-4                 13G                   Page 2 of 7 pages.
- -----------------------                                     --------------------

  (1)     NAME OF REPORTING PERSON                 
          S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS
               IDEX ASSOCIATES, L.P.
          ---------------------------------------------------------------------

  (2)     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP          (a)   [   ]
                                                                    (b)   [   ]

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

  (3)     SEC USE ONLY

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

  (4)     CITIZENSHIP OR PLACE OF ORGANIZATION                      
              DELAWARE  
          ---------------------------------------------------------------------

                       (5)     SOLE VOTING POWER                    
  NUMBER OF                       2,939,199*
   SHARES              --------------------------------------------------------
 BENEFICIALLY          (6)     SHARED VOTING POWER                  
  OWNED BY                        -0-
    EACH               --------------------------------------------------------
  REPORTING            (7)     SOLE DISPOSITIVE POWER               
 PERSON WITH                      2,939,199*
                       --------------------------------------------------------
                       (8)     SHARED DISPOSITIVE POWER             
                                  -0-
                       --------------------------------------------------------

  (9)     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON         
              2,939,199*          
          ---------------------------------------------------------------------

 (10)     CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN
          SHARES                                                          [   ]

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

 (11)     PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)           
              10.0%
          ---------------------------------------------------------------------

 (12)     TYPE OF REPORTING PERSON
              PN
          ---------------------------------------------------------------------

* After giving effect to a three-for-two stock split effected in the form of a
  50% stock dividend paid on January 31, 1997.























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ITEM 1.


        (a)    NAME OF ISSUER:

               IDEX Corporation

        (b)    ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:

               630 Dundee Road, Suite 400
               Northbrook, Illinois  60062

ITEM 2.

        (a)    NAME OF PERSONS FILING:

               IDEX Associates, L.P.

        (b)    ADDRESS OF PRINCIPAL BUSINESS OFFICE:

               c/o Kohlberg Kravis Roberts & Co.
               9 West 57th Street
               New York, New York 10019

        (c)    CITIZENSHIP:

               Delaware

        (d)    TITLE OF CLASS OF SECURITIES:

               Common Stock, par value $.01 per share

        (e)    CUSIP NUMBER:

               45167R-10-4

ITEM 3. Not applicable

ITEM 4. OWNERSHIP

        (a)    AMOUNT BENEFICIALLY OWNED:

               As of December 31, 1997, IDEX Associates, L.P., a Delaware
               limited partnership, was the record owner of 2,939,199 shares of
               common stock of IDEX Corporation. As of December 31, 1997, KKR
               Associates, L.P., a New York limited partnership, was the record
               owner of 5,814,393 shares of common stock of IDEX Corporation.
               KKR Associates, L.P. is the sole general partner of IDEX
               Associates, L.P. in which capacity it may be deemed to be the
               beneficial owner of the shares of IDEX Corporation common stock
               beneficially owned by IDEX




                               Page 3 of 7 pages.

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               Associates, L.P. Henry R. Kravis, George R. Roberts, Paul E.
               Raether, Robert I. MacDonnell, Michael W. Michelson, James H.
               Greene, Jr., Michael T. Tokarz, Edward A. Gilhuly, Perry Golkin,
               Clifton S. Robbins and Scott Stuart are the general partners of
               KKR Associates, L.P., and Messrs. Kravis and Roberts are also the
               members of the Executive Committee of KKR Associates, L.P., and
               in such capacity may be deemed to share beneficial ownership of
               any shares of common stock of IDEX Corporation that KKR
               Associates, L.P. may beneficially own or be deemed to
               beneficially own, but disclaim any such beneficial ownership.

        (B)    PERCENT OF CLASS:

               10.0%

        (C) NUMBER OF SHARES AS TO WHICH SUCH PERSON HAS:

               (i)    Sole power to vote or direct the vote:

                      2,939,199     (after giving effect to a three-for-two
                                    stock split effected in the form of a 50%
                                    stock dividend paid on January 31, 1997.)

               (ii) Shared power to vote or to direct the vote:

                      -0-

               (iii) Sole power to dispose or to direct the disposition of:

                      2,939,199     (after giving effect to a three-for-two
                                    stock split effected in the form of a 50%
                                    stock dividend paid on January 31, 1997.)

               (iv) Shared power to dispose or to direct the disposition of:

                      -0-

ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS

               Not applicable.

ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON

               Not applicable.

ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH 
        ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING 
        COMPANY

               Not applicable.



                               Page 4 of 7 pages.

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ITEM 8.  IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP

               Not applicable.

ITEM 9.  NOTICE OF DISSOLUTION OF GROUP

               Not applicable.

ITEM 10. CERTIFICATION

               Not applicable.









                               Page 5 of 7 pages.


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                                   SIGNATURE


               After reasonable inquiry and to the best of my knowledge and
belief, I certify that the information set forth in this statement is true,
complete and correct.

Date:  February 13, 1998


                                       IDEX ASSOCIATES, L.P.

                                       By:  KKR ASSOCIATES, L.P.
                                       Its: General Partner


                                       By:    /s/ Salvatore Badalamenti
                                           ------------------------------------
                                              Name:    Salvatore Badalamenti
                                              Title:   Attorney-in-Fact








                               Page 6 of 7 pages.


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                                 EXHIBIT INDEX




Exhibit 24 - Power of Attorney







                               Page 7 of 7 pages
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                                                                      EXHIBIT 24



                               POWER OF ATTORNEY


         Know all men by these presents that Henry R. Kravis does hereby make,
constitute and appoint Salvatore Badalamenti as a true and lawful
attorney-in-fact of the undersigned with full powers of substitution and
revocation, for and in the name, place and stead of the undersigned, (both in
the undersigned's individual capacity and as a member of any limited liability
company or limited partnership for which the undersigned is otherwise
authorized to sign), to execute and deliver such forms as may be required to be
filed from time to time with the Securities and Exchange Commission with
respect to any investments of KKR 1996 Fund L.P. or KKR Associates L.P.
(including any amendments or supplements to any reports from schedules
previously filed by such persons or entities): (i) pursuant to Sections 13(d)
and 16(a) of the Securities Exchange Act of 1934, as amended (the "Act"),
including without limitation, Schedule 13D, statements on Form 3, Form 4 and
Form 5 and (ii) in connection with any applications for EDGAR access codes,
including without limitation the Form ID.



                                        /s/ Henry R. Kravis
                                        -----------------------------------
                                        Name:  Henry R. Kravis


January 31, 1997