hey Jimmi, welcome to the garage - searching this forum a bit should give you more than you want to know about an alternator upgrade for AD trucks - there is no year specific alternator, you just need to find the mounting brackets that work with your engine [I think ones from newer Chev 6's can be worked] and get whatever alternator you can find at a reasonable price .... see
this page to learn some about the differences in one vs 3 wire - I'd go with the 3 wire myself
Bill