I am replacing the gas tank in my '85 z28, and before i get started i want some advice from people that have done it before. My main questions are: is the gas tank in my '85 the same as the tank from my '91? and, do i need to take the rear axle out to get the gas tank out? any other advice is welcome too...

 

I replaced mine in my 85. For some reason SPectra lists a different part # for 91. It was a pain to do. I had access to a lift so we didnt have to remove the rear but we had to drop it and let it hang. Then it took a lot of finagiling to get it in there. We ended up triming the body a little. But the only other problem was that I had to use a newer gas cap. The old one wouldn't fit. And their tech line couldn't help me. Maybe this will help you a little.

 

i took my axle out and had the body up on jack stands relatively high. Apparently 91 was the replacement that was made for all preceding Fbodies. There will be rumors of internal changes to the tank that provided better usability in hard braking and cornering to not starve the engine for fuel. It should be the same cosmetically, but many as mentioned above, will need a newer gas cap. Other than that it's relatively straight foward. No trimming was needed on my vehicle, although i did clean up the tank and spray some etching primer to further protect the life of the tank, and i had to squeeze the tank back into the car (similar to getting it out), and it scratched the paint, so i had to fix that. It is a tight fit, but many have done it including chevy dealers for the last 20 years w/out modifying the body. Modifying the body will only make it easier for you now and in the future.

 

yeah I have the gas cap for it. where was the trimming needed, or where might i need to modify the body?

 

We had trouble getting the filler neck through the hole in the body and we just trimmed it a little bit. The neck on the new Spectra tank was bent a little bit different so it was a little harder to get in. The part # I got was for 85-87.

 

I just replaced the tank in my 85ta. The rear end doesn't have to be removed. The two bars that connect the rear end to the frame must be removed and acourse the exhaust must be removed also. This is not a fun job. It was a real pain reinstalling the tank but I did it by myself and I do not have a lift. I would think a tank from a 91 would fit but the sending unit may be different.
I didn't have to trim anything.

 

I finally got the tank out after removing the axle, it came right out. I think i'll drop the axle on my '85 when i put the tank in, that seems to make it a LOT easier.