Charging system problem

Ive got a 77 F-150 4x4 with a 6.6(400) and a C-6.

My question is, the last few days I've been upgrading things inside the truck. I swapped a gague cluster from a 79 F-350 into mine b/c mine was falling apart. The factory one had the dummy lights for the ALT and OIL pressure. THe new set of gagues has oil pressure and charging gagues instead of the lights. Is their any way to get the gagues to work that took the place of the dummy lights?

Now here's the main question. After I swapped the dash, the truck is running off of the battery. It seems as though the alternator is not even charging at all. I've tested both the battery and alt, so I know its the alternator or something between the alt and battery. The dash wouldn't have anything to do with this would it? It seems like it just started this after I did the swap. The only thing on the dash I have hooked up is the fuel and temp gauges and the dash lights for night.

Any suggestions? I don't want to buy a new alternator for this thing if I don't have to.

ttt

I got more answers out of the Silverado Forum than from here. Go figure??:eek7: