Well I got my 8-32 form tap and was able to tap my first attempt. And I can machine the rubber using high speed turning and very light cuts. So I think I'm going to be using this for my car. I like the thicker rubber padding and know it should last.
All I can think of with the problem tapping that 304 SS is when I drilled the hole it "work hardened" the SS. I tried to heat it and cool it fast and even tried cooling slow but I still could not tap it using the normal cutting tap. Anyway, I bet using a form tap for aluminum would be great since you don't get chips and would not have to keep backing out the tap to clear chips.
So this SS is a little discolored from my heating when I tried to soften the metal.
I'm thinking of maybe using a bigger bolt for the engine cover bumps so I can use the same rubber bumpers for those.
I do think the passenger side was always 50 mm long and the drivers side 40 mm. I had to cut my new one for it not to bottom out on the drivers side. The parts list does show different part numbers but it says 2 of each in the parts list.
Maybe it's just some VINs that require the two different lenghts.