I've got an 80 f150 with the 351w and the alternator and the regulator are both new. I traced down the wiring to all, are hooked up to where they need to be, i think. anyway, the thing is still running off of the battery. Any suggestions?

 

I would have the alt tested(bench tested) I have seen rebuilds not work out of the box also is there a voltage regulator between the battery and the alt? That could be a source as well.