Every time a friend of mine and I have to pull something out of the lake, and I'm not talking a boat trailer at the ramp, we use his 2007 GMC. That thing has some kind of traction control on it that allows his fat, wide, low profile totally street tires to not spin. Ever.
If I hooked my 4x4 up to it (all stock for 1971 with no traction control, only posi) the first tire that started to lose grip would be half way to China if I didn't get off the gas.
GM has some kind of traction control in that '07. My friend just stays on the gas. He claims "a governor kicks in" when he pushes the go pedal down to the floor. I'm guessing the computer kicks in to limit the R's and the brakes start pulsing on the wheels that are trying to slip.
EVERY time we pull something nasty like a broken boat dock or a heavy boat lift out of the lake that thing amazes me.
Put that system in a 1971 4x4 to impress me. (Then tell me how you did it so I could too.
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The engine in the truck is nothing special. A standard 5.3 liter. I think what you'd need is the computer and the front and rear brakes.
Regarding the rear steering, another friend who plows for extra beer money in the winter picked up a tahoe with rear steering. He said that thing is amazing when you have tight plowing conditions like say at a town home complex. It would be REALLY cool if you could do traction control and rear steering.
In the same breath, if all you're doing is pulling a car in the summer I wouldn't bother with the 4x4. I'd get a 3/4-ton or 1-ton 2wd and build it right.