What amp alternator do I have?

Johnpaul Ragusa · July 6th, 2009

I am about to try my hand at mechanics. I have NEVER been under the hood but figure I need to start sometime. My wifes 72 Cutlass Supreme needs an alternator (I think) and I have no idea what amp the existing one is. How can I find out? NAPA auto can order me one but there are different amp levels to order. Can I identify it somehow?

Thanks all! Wish me luck

jimkf · July 6th, 2009

Your car probably has the 60 amp unit...that was the most common. The higher output units..up to 94 amp, were only used on cars with AC and power windows, door locks and rear window defogger. Some wagons also used the heavier unit. If you take yours off and take it to the parts store, they can ID which one you'll need. The good thing about 70s GM alternators, a set of basic sockets and wrenches will be all you need. Don't forget to unhook the battery first!

F&J · July 6th, 2009

It should be stamped on the case, like 55A , etc

Johnpaul Ragusa · July 6th, 2009

Thanks guys! Assuming I don't fry myself I'll keep you updated

Commodore · July 6th, 2009

Well, first off does it have AC? Does it have Internal Voltage Regulator or External Voltage Regulator? There should be part number erther stamped on the alternator or on a tag. What is it? Same for the External Voltage Regulator if it has one.

Robin Coleman · July 7th, 2009

jimkf is on the mark with his advice, but please make sure you disconnect the NEGATIVE (the black one) battery cable first.

58Mustang · July 7th, 2009

I would rebuild the old one. It is very easy and well within the capabilities of a backyard tinkerer. Your new "rebuilt" is likely to be an offshore piece o' crap, not worth the TNT to blow it to hell.