I spend a lot of time lurking this and other sites seeing and learning how others are restoring their Seacrafts in preparation for the day I get my 23’ inboard dream boat. Fuel cell replacement seems to be very common, and I found an interesting article on how to mount a tank correctly. One common mistake pointed out is the use of rubber pads. The carbon in the rubber acts as a cathode to the aluminum tank inducing galvanic corrosion.
I think this link may be of interest for anyone replacing a fuel cell or inspecting one.
fuel tank replacement
Jay