I just had an aluminum tank made for a PSC34, I'll get the manufacturer's name for you shortly (I believe he is in California). I had the bottom and sides coated with Rhino Lining (see Marine applications on www.RhinoLining.com
) before I installed it back in the boat so it can't be exposed to salt water in the bilge again, thus causing the tank corrosion that is so common on the older PSCs (surveyors recommendation, worked out really well).
I understand that stainless is not recommended for fuel tanks because if they fail, they fail catastrophically. If your bilge is wet, oxygen deprevation may be a factor with submerged stainless.
After watching what has happened with marine fiberglass tanks when ethanol was introduced for gasoline engines (i.e., ethanol acting as a solvent and slowly disolving the tanks), I'm a bit nervous about what could be in store for diesel fuel down the road, thus I was leary about going with a fiberglass tank.