The big news since the autocross is that my original alternator was dead (which killed the battery while we were there). A lot of poking, prodding, and book-looking finally led me to a few points. The Motorola unit on my car is the original one, and is 33 amps. The later AMC’s switched to the 10si style GM/Delco unit (one of which I have in my garage), but they also totally switched the v-belt system and brackets around. You have to get the whole setup to have a clean swap. Luckily my dad has a local guy down in Florida that rebuilds these units into the original 65amp HD spec for reasonable. Turns out, the original design is actually for tractors and quite a few industrial engines. So months later, I finally have a completely rebuilt alternator that bolts into the factory location!
