Heavy Duty Alternator

I have one of those in my garage...and its the siezed one. The footprint on these ones is actually bigger than the OEM mopar alternator.

For a small alternator, you'd want to swap a v-belt pulley on to a CS-121 Delco. This is what powermaster sells as a race alternator.
http://store.summitracing.com/partd...4294880793+400345+4294880709+115&autoview=sku

they're tiny. get one off a late 80's or early 90's cavalier or sunbird with the 4cyl and buy an $8 v-belt pulley.