Data taken from CompaqDocument Number: 107315-025, Volume 1, January 1996
If two numbers are given, the first is an assembly part number, and the
second is a replacement part number. You probably want the second if you
are fixing your aero.
   
                  System Boards Assembly Spare Part System
                  4/25 System * 003209-002 197241-001 4/25
                 4/33C System * 003489-001 199222-001 4/33C
                                      
                       * Without PCMCIA eject rails.
                                      
                  Memory Boards Assembly Spare Part Option
              4 MB Expansion 003296-002 190565-001 190532-001
              8 MB Expansion 003308-001 190596-001 190597-001
                                      
                 Misc. Internal Assembly Spare Part System
               Backlight Inv, mono 003215-001 190522-001 4/25
                   Display Panel, mono -- 190624-001 4/25
              Backlight Inv, color 003492-001 199223-001 4/33C
                  Display Panel, color -- 199232-001 4/33C
                Trackball Assembly -- 197286-001 4/25, 4/33C
                         Trackball, Matte* -- * --
                 Display Clutch 190638-001 185099-001 4/25
                 Display Clutch 190638-002 199336-001 4/33
                                      
    * A Trackball (Matte), retainer ring, and/or trackball cleaning kit
   may be obtained directly by U.S. customers by calling 1-800-841-2761.
                      In Canada, call 1-800-952-7689.
                                      
                      Misc. External Spare Part System
                     AC Adapter 190621-001 4/25, 4/33C
                 Automobile Adapter 190551-001 4/25, 4/33C
                Convenience Base Unit 190568-001 4/25, 4/33C
                Mobile Port Expander 197364-001 4/25, 4/33C
           NiMH Extended Life Battery Pack 190626-001 4/25, 4/33C
           NiMH Standard Battery Pack (w/spacer) 190697-001 4/25
                   Battery Spacer 197317-001 4/25, 4/33C
                  Trackball Cleaning Kit * 184115-001 All
                                      
    * A Trackball (Matte), retainer ring, and/or trackball cleaning kit
   may be obtained directly by U.S. customers by calling 1-800-841-2761.
                      In Canada, call 1-800-952-7689.
                                      
              Hard Drives Drive Type Min ROM Spare Part System
                   84 MB 65 System 190660-001 4/25, 4/33C
                     170 MB 65 System 190661-001* 4/25
                     170 MB 65 System 199275-001 4/33C
                  250 MB 65 System 199233-001 4/25, 4/33C
                                      
              * Currently restricted to 4/25 for FCC approval.
                                      
                     Modems Assembly Spare Part System
              SpeedPaq 144/P PCMCIA 198112-001 194131-001 All
             PCMCIA 14.4 Data + Fax * 149776-001 194097-001 All
           PCMCIA 2400/9600 Data + Fax 149775-001 194098-001 All
            SpeedPaq 192 PCMCIA Fax Modem 004234 187123-001 All
                 192 PCMCIA Fax Modem 004329 188512-001 All
                 288 PCMCIA Fax Modem 004467 189661-001 All
                                      
   * Obsolete. Replaced by 187123-001. Must also order 187145-001 (modem
                               adapter kit).
                                      
                    External Diskette Spare Part System
          PCMCIA External 1.44 MB Diskette 190563-001 4/25, 4/33C
                                      
                     Cables Used With Spare Part System
                 Display Cable Mono display 197238-001 4/25
                Display Cable Color display 199258-001 4/33C
             Communication Cable WinLink 197318-001 4/25, 4/33C
             Trackball/Speaker Cable -- 197312-001 4/25, 4/33C
                                      
                         ROM Information Spare Part
                             ROMPaq 181088-001
                                      
                      Power Supply/Battery Spare Part
                          Power Supply 190521-001
                          Clock Battery 117099-001
                                      
and as mentioned in various posts to the list:

replacement battery cover and Memory upgrade door 197239-001 (Gallivan)

you can also take a look at Gebhard Markus's page of parts: 
http://kakadu.rz.uni-passau.de/~gebhar03/aero/parts/parts.htm