Assuming your wiring is correct for a 65, you have a 1 field wire voltage regulator.
It should look like this.
View attachment 1715870849
Your alternator origionally would have looked like this.
View attachment 1715870850
The parts store replacement would have looked like this (most likely) note the connector (blue arrow) is cut off. It is grounded to the frame of the alternator.
View attachment 1715870851
If you were given an alternator that looks like this ( note both connectors are intact)
You might have the wrong alternator
View attachment 1715870853
With an ohm meter you can test to see if the alternator you were given was an isolated field (2 field wires) or non isolated field (1 field wire) alternator
My bet though is the catastrophic failure of the alternator killed the voltage regulator
