I am just grasping at things here with your gauges. Have you looked in the 3rd Gen Electrical Section. Did you contact the company you got the refurb'd PCM from. Sorry I am not a truck expert just enjoy having mine. I will do some more searching!
Hey Shawn I hope you can. I had a weird problem where truck would cut out occasionally and then the gas gauge would occasionally swing to empty and the light would come on, didn't take long for the truck to no longer stay running without feathering the pedal. Assumed it was gas flow issue and replaced my fuel pump, that didn't make any difference, all same symptoms stayed. I had a 601 error on the PCM since I had it (2 years) decided to give it a shot and got a refurbed PCM. The truck runs pretty darn good now, however all my gauges are dead and some of the lights are lit. I checked a bunch of grounds and cleaned them up. If I put the old PCM back on the gauges do the same thing but truck won't run like before.
Any troubleshooting tips on the gauges would be greatly appreciated.