Rear wheel drive

Sell the truck and buy what you want. To modify yours will require a transfer case, front drive shaft, shorter rear drive shaft, modifying the transmission, replacing the Body Computer, Engine Computer, Integrated Power Module, and instrument cluster, adding the shifter and linkage, cutting out and replacing the floor pan to accommodate the shifter, replacing the cross member under the transmission, replacing the front suspension to accommodate the front axle and differential, replacing the front springs with stiffer ones, replacing the brake system hydraulic combination valve with a different rear proportioning valve, installing larger rear brakes and wheel cylinders to maintain the balanced front-to-rear braking with the larger front brakes, installing a larger radiator, ... And those are just the things I know for sure are different. By the time you're done buying just the parts, you'll have way more invested than the cost of a new truck that's already put together and working right.

I have a friend who buys and rebuilds only smashed Chrysler products. I've helped him on a few trucks including one that had the engine pushed back so far the floor was wrinkled. We had to cut out and replace the firewall and section where the 4wd shifter pokes through. It was not a fun job. No mechanic will consider taking on this modification because there's just too many things that are going to go wrong and not work right, so you're going to have to do this yourself.