If there is no voltage from the alternator, it may not be getting the essential Pre-Exitation current required for initial voltage build-up.

Unless the battery is totally flat, try this test—turn the Key to ON and make sure the BATT light comes on, along with Brake Failure, Parking Brake, and Bulb Failure.

Those lights should all come on by grounding via a small red wire to tha Alternator D+ terminal. This provides the pre-exitation current.

1) If no lights—check to see if the red wire is in place at the alternator.

2) If it is in place, take it off and ground it while checking the dash lights again.

3) If you get dash lights with wire grounded, but not when connected, check the Alternator ground wire. (Lower,inner rear case bolt to mounting bracket bolt. Fat Blue wire, hard to see. Check each end by feel at least.)

4) If you don't get the lights with red wire grounded, the circuit is OPEN somewhere between the dash and the end of the wire, typically at the gray firewall connector on the right side of the FW.

5) If those lights DO come on with Key On, check to be sure the red wire is on D+, not fallen off and touching ground.

This doesn't test the regulator or alternator, but without it, nothing happens.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.