This idea is inspired by the drive systems found on the Jeep Hurricane concept and on the Batmobile in "Batman Begins."
Start with a longitudinally mounted engine, with a transmission and differential bolted on directly, essentially a transaxle like those found on mid-engine supercars and on newer
Corvettes.
The halfshafts coming out of this transaxle would each go to two differentials on either side of the transaxle.
Out of these, a halfshaft runs to each wheel, where bevel gears, universal joints, and trailing-arm suspension connect them to the spindles. It might be possible to replace both the front-back halfshafts and the trailing arms with single torque tubes running to each wheel.
The center differential, then, works like the front and rear differentials in a normal 4WD vehicle, and the two side differentials control the front-rear distribution like a center differential or transfer case in a normal 4WD car.
This system has the advantage of the symmetrical drivetrain layout and independent suspension normally associated with AWD cars; but the ruggedness and modular design of a 4WD truck.
Since all three differentials are within a few feet of each other, it would be much easier and simpler to install and control things like torsen or locking differentials. It also offers better ground clearance than either system, because there are no axles or A-arms between the tires to get caught on obstacles.