Tail light gaskets/Reverse light gaskets/Screws

[Big70]

OK I'm putting in new tail lights and cleaned up my housings. My question is, are there two different gaskets between housing and plastic lenses? it seamed like there was a thick rubber in the housing and my local c10 shop said no there is only the foam style ones that he can get me.... The other question I had is when I removed the factory housing there were rubber like bushings around mounting screws and my pops said there were there to keep the housings from rattling around and knocking out bulbs and what have u? That is another part my c10 shop has no clue about... Im I missing some thing here? The gaskets I got with my new lenses seam way to thin compared to the factory ones I pulled out. Any help is always good help thank you!