If you can't put one of the ones that FF posted about.... take a look at the alternators that are made by ARCO in Pensacola, Fl.....
ARCO Marine Alternators,Starters,Tilt-Trim Motors and Marine Electrical Parts
Tread very carefully with ARCO, they are rebuilders of tons of marine gear.
Read carefully to assure its NEW , not a rebuilt with an amp kit.