maybe you should try a different supplier. i have gotten one for my 75 that does either way. didn't cost anymore for it as all you had to do was pull out a cap they have over the plug connection. the plug is some sort of jumper to be able to use it with single wire.

Thanks eddie! I just went and got one like you described. I was just getting mad because there was a nice chrome 100 amp one on sale but it was a single wire. This is my first time working on a corvette and GM for that matter. I've used GM single wire alts before on older trucks, but sharks stock one with the plug on the side was confusing me  I got it figured out though. This site was really helpfull breaking down the differences between all the Delco alternators.