2008 Chevy 2500HD Work Truck

2008 Chevy 2500HD Full Size Work Truck, 6.0L Gas PS PB Auto Trailer Pkge, Bed has Tommy Lift. Truck was run into a tree at very slow speed, just pulling out of driveway. Damaged parts were taken off for replacement and never put back on. Truck had a service body on it. I took it off for another truck. The bed off the other truck will go with this truck. That bed has a Tommy Lift. Differential is included (pictured). Truck will not start now because things are disconnected.