you'd be better off just buying a 4x4. the conversion is possible but the expense and work would be outragous. like phily said, it is possible and i agree with the conversion on the chevy, to get away from the ifs. but the dodge has great frontends from the factory (the dana 60), which is what people swap into the chevy's. (usually out of a 04 and earlier ford for the leaf spring set up)
but if you insist on getting a 2wd, your best bet will be to find a whole other donar truck for parts. because you will need a bunch of parts... like a front end, tranny, transfer, driveshafts, brackes, and probably crossmembers just to name a few.
good luck either way!