Round back or Square back alternator?

[Some Car Guy]

While I’ve done it without changing anything other than grounding the field, you could do a real slick job of upgrading it all with a Year One harness and a 1970 bracket for the voltage regulator. The harness has the electronic ignition wiring, plus the electronic regulate, plus the two fields. The bracket bolts where your mechanical reg does and the. You bolt the later reg onto that.

 

[AR67GTX]

You can probably borrow the necessary pulley puller at an auto parts store.