I know that they are different sizes in the amount of fuel they hold but are they interchangeable. We are working on a S5 GTU and the fuel pump went out, pulled the pump and the inside of the tank was rusted out really bad(the car had sat for a couple of years). I have a S4 T2 fuel tank from when I went to a feul cell, is it possible to swap the two out?

 

so about those tanks?