Differntial internals are inserted from the top (horizontal plane) on G-742 vehicles - conventional differentials go together from the vertical plane.
Torque rod - when you throttle up a vehicle, the force that turns the wheel also tries to turn the axle in the opposite direction. On a typical rear wheel drive passenger car this force is resisted by the spring - which does allow some movement (and wheel hop under severe power applications). The torque rod adds rigidity to the suspension, to counter these and as well as side to side forces.
Sprag - often misapplied term. When applied to 6x6 trucks, what most people mean is that the truck is equipped with automatic front axle engagement via overrunning clutch. The same system is used on G-744 and 809 series trucks. Two clutch units are provided in the transfer case, one for forward, the other for reverse. On the 2 1/2 ton, the selection of sprag is achieved by a mechanical linkage attached to the shift top. On the five ton an air solenoid did this - again, linked to the shifter. The mechanical linkage required periodic adjustment, which many folks in and out of the army don't do. It also requires that the driver move the shift lever through first (even if starting in second) when coming out of reverse, as this action selects the "forward" clutch unit. Beyond that, the engagement of the front axle is automatic in all five forward gears, engaging when slippage of the rear axles is detected. Driver and mechanic laziness are the reasons that the "air-shift" transfer case was developed. In this instance front axle engagement is controlled by an air valve on the dashboard.
I've got trucks of both types, and have had no trouble from either.
Hope this helps,
David Doyle
