70 duster not charging .

On a isolated field alternator the field coil gets its ground (green wire) from the voltage regulator.

The blue wire should be at or near battery voltage.

The fields coil will show + voltage on both sides, If the green wire is disconnected from the terminal on the alt

Do as 67dart273 said, then start and check bat charging voltage. It might be up near 18v so don't run it that way very long.