GM alternator info please

Could someone please help me with some info? I've always known that GM used only a handful of alternators over the years (except recently). I have a 73 Impala Wagon with a 454, and the alt is going. The battery at rest shows 12.8v on the multimeter, but testing the battery while its running only shows 11.3 :)

There were a few different alt cases and my memory is hazy, but weren't they something like a 10R, 12R, and something else? I also know that within a certain case size there were slight differences in the casting of the housing so it would fit different blocks. I use this car as my work vehicle (I'm a contractor) and I have plans for very moderate stereo upgrades, but I am going to be running a serious power inverter to do things like charge my cordless tool batteries and run my laptop, so I want some serious power output. I'm thinking at least 100, maybe more like 150 amps would be nice. I know late-model cop cars and Impala SS had 140, but they are an entirely different case and a serpentine belt.

Should I go aftermarket? Should I try to cross reference part numbers with a newer car? Anyone know what size case mine is? Thanks bunches

i Have A Suggestion Of Using A Powercap Capacitor For Your Aftermarket Stereo Upgrades, That Should Help With Some Of The Power You Will Be Running, I Have Heard About Some Dodge & Ford Alternators That Carry 150 Amps, Maybe There Is A Way That You Can Adapt Either Of Those 2 Alternators Or You Can Build A Custom Mount For The Chevy Cop Car Alternator, Or Im Sure You Can Find A Shop That Rebuilds Alternators, Im Not Sure If They Can Upgrade The Alternator You Have Now, But It Would Definately Be Something To Look Into, Just Some Suggestions, I Hope They Were Of Some Help To You, Peace

Any good parts guy/store should be able to fix you up with a high powered alternator that'll fit. I've mixed and matched alt. applications on a few of my GM's. At one time, I had a chevette alternator on my '83 Caprice. Worked fine(only 85 amps).

If you do find an alternator with the right amperage for you, and the pulley is a serpentine type, you can change the pulley easily with an impact gun. Just be sure to measure the back-spacing so you don't chew up a perfectly good belt.

Being that your car is a wagon, with a big block no-less, I would suspect that you already have all of the heavy-duty goodies on it. What amperage are you running now?