Fuel tank question

[e46_dude]

First of all i am new to the e30 world. I bought an 84 325e turbo and love it, then i bought a 1991 318is dirt cheap but it wasnt running. I am working on the car but the car sat for like 2 years and the fuel tank is rusted inside. Does anyone know what all fuel tanks will fit this car? There are alot of e30's that are constantly being parted but i want to make sure they will fit before i buy one.

any help is greatly appreciated