The assist leaf springs would be available on either a 1.5 OR 2 ton, so no help there. Not a LOT of difference between the two, in fact, I believe it's a matter of tires and suspension, more than anything.
Truck as stock would have the (in)famous SM-420 4-speed, which is synchronized in the upper gears, real work-horse tranny. Two-speed rear is likely. Look for a vacuum shift mechanism on the front of the differential.
My two cents worth, anyway . . .
-Michael
