The late ones have the ebony board, which some people might regard as a quality plus, and among these a few even crept out with a three piece (not single piece like the bulk) neck with no scarfed headstock, which I guess is another quality argument. You could say that the late G-3s had a Victory influence creeping in which was by that time already the mainstay of Gibson bass production. Personally, I think the early eighties stuff is workmanship-wise a bit better than some (not all) of the seventies stuff, more attention to detail if you like, probably because production numbers for these models were already much lower.