Ok, here are the last comparison pictures besides springs. The proper GM ones are Special Order, still waiting.
Almost everything can be substituted for a cheaper new part vs Genuine GM. The upper seat, bearing and wedge in the mounts are all plastic. Only thing a kit won't have is the dust shield (#5 in diagram) and wedge (#4). Both of mine are in reusable condition. You will need the wedge. Dust cover #5 is not required.
These are the two mounts I got. The Portugal one has so much age on it, I'm concerned about even putting it in. These two AC Delco mounts are the same. Idk about other brands.
(blurry, sry)
Right is the new old one. Looks crusty.
I went with Moog K201271 bellows vs GM. You won't have to go to the trouble of removing the stock bump stops. Although not pictured on parts sites, Moog comes with a new one.
The yellow bearing that came with the Delco mount above has some play around the center circle. The Canadian GM bearings have zero play.
Do you need the Genuine GM ones? No. The possible difference in longevity will be negligible compared to the life of the strut(s).
About the only stuff you can't reuse or buy cheaper is the actual struts and springs. The old isolators will be flat and wrecked, but any replacement is fine.
Actually, a user on fb said they don't use isolators. Apparently, you can change your ride height by just leaving those out.
I dunno, they make springs for that ..kinda sounds ghetto to me but what do I know. I'm keeping mine in, lol.
Alright then, till next time
