new alternator, new battery, won't charge

Just installed a new alternator and battery as they were both bad (Bench
tested both). When the truck is running I am getting a little over 12V to the
alternator. The dash gauge for the battery stays at the bottom line. When the
truck is running and the battery is disconnected the truck dies. Of the two
wires on the plug into the alternator, the wire that goes hot when the key is
on (plug green/red) gives off a 10V signal. Is that right? Seems kind of high
for a wire that tells it weather it is on or not. I checked this when the truck
was on and the wire was unplugged. The wire that sends power to the
alternator all the time (plug yellow/white) shows at the same voltage as the
battery and so does the wire that is bolted to the alternator (Large black/red).
My diagnosis indicates that there is a problem somewhere in the wiring
harness between the alternator and wherever all these damn wires go, but I
want to make sure first because the wiring harness runs through the middle
of the motor and i'm not looking forward to tearing the truck halfway apart if I
don't actually have to.
My truck seems to use a Fusible link if I understand it right (Large red/black
wire runs to the fuse box and bolts to a plate on the outside of the fuse box).
Thoughts and ideas? Nothing I have found online actually answers any of
my questions related to this.