If talking about actual GM Delco alternators, most reman units use the cases off anything 10si or 12si so the numbers never match. But you can put the blade fan from a 10si on a 12si 80's type to backdate the appearance but get extra amps. It won't work the other way around in putting a 12si disc fan on a 10si case. Otherwise, there's a whole lot of the chrome type, made who knows where, with one or 3 wires, but also in various finishes. Others will comment on that type. I simply have my original 61A uprated to an 85A but appearing stock, nothing crazy for a stock car. No fans or stereo or big lights etc.
You can probably buy the exact unit you already have, just in bare alloy, if it works ok.
