... interlocking upper (top & bottom on shock shaft) insulators designed to keep the shock centered in the upper mounting hole on the frame. ....
Yepper. Getting the nibs on the upper bushings to seat properly in the hole is critical in assuring the shaft does not come in direct contact with the metal frame and create the perfect squeak-maker.
Another thought is that whenever upgrading one part (especially a big performance gainer as Bilsteins) it tends to show up other weak spots like perhaps a nearby loose body or motor part.
\'96SS SOB: SSRI, Herter Tune, Tri-Y II, , 3000 Edge, F/HO bars, METCO extendeds with CV MMC, Bilsteins, currently Vredestein Ultrac Sessanta (315/35 rear). Finally, wait for it... LT-4 knock module!
\'96FWB BUW-Butt Ugly White: PCMPerformance tune, HDFA w/ swissed filter, 1/2 SLP s.s. catback with H- and Flow Super 50s, oem opti rebuilt 3 times, SS Bars, METCO LCA, Airlift 1000, Monroe SS, PowerTrax No-Slip, CTS wheels with +1 rubber. Finally, yes again... LT-4 knock module!