Is there any difference between an early (midship pump) and late (front pump) fuel tank?

I know the top fuel fill is different, the early having metal expansion tank as opposed to a plastic one on the late models.

have a 73 with possible rust issues in tank. will later tank fit?

Howard I just pulled out the tank on my 74. It looks really good no rust issues. Right now it is set up for carbs but the plug can easily be removed on the return line.

The tanks have different P/N's but I think the only difference between them are the brackets for the vapor canister. Other than that they are interchangable after you change the outlet tube to suit your particular fuel pump setup.

Thanks, John. Joe, I'm not sure it's bad, and think I have one locally. Will contact you if I need it.

Yes. And you can easily use the tank filler top and also the expansion chamber (if the original car/tank had one) from the original tank if you prefer.