97 is a f250 diesel and I was wondering if they were drastically different or if it would work in my 91 f250, 351 FI after I drain the diesel.
Thanks for your help to a neophyte

 

A few years ago I put a front diesel tank out of a '97 F-350 into my '89 150. Dimensionally the tanks were the same, but the hole for the sending unit/low pressure pump was a little different. It's been a few years since I did it, but I think I had to bend the locating tab for the sender on the diesel tank so I could put the gasoline sender in the correct position. A little extra (and unexpected) work, but it's still holding gasoline.

The rear tank you have will most likely fit right in, but expect a few bumps in your road in regards to the sending unit.

HTH
Pat