Auto Parts: 1984 alternator, cadillac eldorado, ac delco

Question
I have a 1984 Cadillac Eldorado with an alternator that can only hsndle about 50 amps, but have a high performance stereo system with an auxillary battery that pulls about 45 amps,  I need a larger alternator with @ 100 amp capacity that is compatible with the 4100 engine size.

Answer
This can be tricky Carl.  Actually, I'm dealing with the same issue as yourself with one of my Jeeps - trying to find a suitable 140A alternator from a donor vehicle to replace the 90-amp stocker.

Anyway, since you're driving a GM vehicle, you may find the best luck by becoming completely familiar with the alternator you have, and looking around in some junk yards to see what has the same case casting.  Your best bet for finding bigger alternators may be to check out some SUV's, like Blazers, Suburbans, trucks, etc. of GM/AC-Delco variety.  I think you will eventually find one that will fit your application.  Good luck!