In 69/ earlier, alternators normally have one field/ brush connection, the other is grounded
In 70/ later BOTH field/ brush terminals are supposed to be insulated from ground
So check the one you bought, and you can usually tell visually by the insulation washers or lack of them.
The 69/ earlier has one field connection
the 70 and later (to convert) needs two field connections both insulated from ground and add one more wire (if converting a 69 to a 70) and buy the new VR
