Alternator polarity?

Mattax said
Look at the wiring diagram in the '72 shop manual.
The letters next to the wire will be something like J2A 18DBL. That translates
Run (Ignition 1) circuit. 2nd section branch A. 18 ga Dark Blue
I know the earlier cars, it was typically 18 ga for A-bodies and 16 ga for B-bodies. '72 might be the same.

Here's that circuit connection to the battery based on '73. A '72 v8 Calf car would be similar.