We have a lot of people that are having to change fuel tanks. Most of us appear to be doing our own work. Something I have not seen discussed is the use of galvanized fittings or pipe. You do not use galvanized fittings or pipe in a diesel fuel system. Over time the zinc comes off as a sludge in the fuel. The sludge is highly abrasive and fine enough to get through most fuel filters. What it will do is wipe out your fuel injection pump and injectors. Stainless is the best way to go, but black iron is acceptable. Galvanized is not.
The fab shop that made my two new 23gal Aluminum tanks put in brass fittings. The yard that installed my tanks removed all the brass and replaced it with stainless.
good note on the galvanized.