Parts Needed
Insulators -Part #1627359
Spacers -Part #1626368
Bolts -Part #10409029

I have purchased 6 of these to replace all on my 91.

Bushings I purchased were marked 1627359 FWIW, these were listed for the Reatta in the parts catalog at the dealer. Likely they are used for the Riviera as well, I'm guessing that this one part # supercedes all earlier variations/numbers for both the Reatta and Riviera. Anyway, this should settle the confusion over which to use.

They are genuine GM parts, not Delco (GM SPO boxes on all) and got them through my dealer. My price was about $ 23.00 a piece. Granted, I get wholesale pricing (what the dealer would charge a shop with an open account) but that is about a 40-45% discount over retail, so regular price shouldn't be more than about each. Whoever is paying apiece should have brought their wet suit because they are getting hosed by their supplier. I don't have the part number in front of me right now (at office, info is at home) but I will try to post the number I ordered later tonight. It is interesting that all 6 were the same # based on current parts catalog. In the FSM they call out 2 different types based on a color code which would have been stamped on the original parts, probably long gone on our cars with original bushings. Also, the parts I ordered were listed for car code EC97(Reatta Coupe) whereas Riviera is EC57, so the correct ones should be available.

Yes, there are also spacers, nuts and bolts. I did not check on the hardware, but was told by my parts guy while the spacers are available, I should be able to reuse them (all metal part apparently) but that remains to be seen. Hopefully I can get the bolts and nuts removed without any breakage. Hope this helps