Electrical problems

I have the truck listed above 3500 dually. The interior lights quit working, the radio quit working. The only two gauges that work on my instrument cluster are the speedometer and the tachometer. Power seats still work, cigarette lighter still works and my gauge lights still working. Power windows won't even work. I checked the BCM and according to the shop it's still good. For the life of me I cannot figure out what's going on.