Regarding the rear...
Yes, you can buy a complete drop-in "jack-pot", then, you jack up the rear axle assembly, pull the rear wheels, drums, remove the axle retainer plate, pull the axles. from under the car, disconnect the rear u-joint nuts , pull away from the pinion yoke. Place a pan beneath the rear housing remove the 12(?) nuts holding the carrier assy. Don't worry dude, it won't fall off, for sure! Next go find the "BFH" and start tapping the perimeter of the carrier forward of the parting line. If you're lucky, it'll break loose. If not place a wooden wedge in the parting line at several points around the perimeter of the housing to break it loose. Once successful, the lube will start to spill, catch as a possible, then, pry it off the studs. Now dude, be ready for one "friggin" heavy lump of iron.
So, you only have to choose an appropriate form of locking rear. You can choose , TSD, Equa-Lok, Trac- Lok, Detroit Locker, PowerTrax, Auburn, etc. Most reputable companies can supply a drop-in unit and can be installed in the reverse of removal. You only half to add a high quality gear lube and an traction additive, if required.