Alternator not charging, need help!

[mysticclam]

I just completed converting a '79 diesel silverado to gas, diesel was bad, put an olds 307 in. The battery wasnt charging, looked like it was the alternator that came with my junkyard engine. I put the old diesel alternator on, not charging, only showing battery voltage while running. I put a one wire alternator on thinking Id messed up the charging circuit while cutting out some diesel specific wiring. It wouldnt charge. Bought a new standard 3 wire GM alternator after testing the connector and put it on and still not charging. Truck has two batteries, both brand new. Ive tried having just one batter hooked up, didnt make a difference. Alternator case reads a ground.
Bat cable reads 12 volts so i know its hooked up. The wires going to the #1 and #2 posts on the alternator read show 12 volts all the time for one and 12 volts with the ignition switch on for the other. Its driving me nuts cause the 1 wire wouldnt work, it really sounds like the alternators have no ground but they do. Also, shouldnt one of the wires on the connector read less voltage? I have a volt gauge and no charge light that i can find so im not sure how the #1 and #2 wires should work. Doesnt oen go through the light?
Any input would be appreciated.