Will the fuel pump assembly from a 94 work in a 91. Both are F250 with the 5.8L and are dual tanks. Wondering if the pump assembly out of the 94 front tank will work in the rear tank of the 91?

 

It's not a direct swap but it is possible. You will have to change the hard line section as they are shaped differently for front and back tanks and because the electrical connection is different from early to later models. The parts I'm referring to and thier differences can be seen in the pic below. Making the necessary changes is a little more complicated because the electrical connections go down inside the resovoir to the pump so the whole thing has to come apart, you can't just pull off the hard lines and swap them.

 

are the fuel pumps themselves the same? easier to just swap them?