Personally if I were you it would be down to a choice of two carriers, both made by Eaton. A Detroit Locker, or a TrueTrac, depending on how you want to use the truck and want it to behave.
The TrueTrac is an awesome carrier, I have one in my Monte Carlo and love it. It's super smooth and well behaved. It's really for vehicles that are going to be driven primarily on the pavement, though. Reason being is that if you're ever in a situation where one drive wheel has zero traction (like if it's off the ground) then that wheel will be given 100% of the driving force and you'll just free-wheel until you give it some brake pedal to simulate load on that wheel.
The Detroit Locker is a little more violent on pavement, you'll probably hear and/or feel it engage and disengage at low speeds, mainly during cornering. However as the name implies it keeps the drive wheels locked 90% of the time, so you'll never have traction issues if you get one wheel off the ground or on a patch of ice or something.
If you're going to use the truck like a truck, I'd personally go with the Detroit Locker.