GMC 1982 Light Duty Truck Service Manual page 417

The differential pinion gears are m ounted on a differ­
ential pinion shaft, and the gears are free to rotate on this
shaft. The pinion shaft is fitted into a bore in the differential
case and is at right angles to the axle shafts.
Pow er flow through the differential is as follows: The
drive pinion rotates the ring gear. The ring gear, being
bolted to the differential case, rotates the case. The differ­
ential pinion, as it rotates with the case, forces the pinion
Fig. 4B-2--9 1 / 2 " Ring Gear Axle
gears against the side gears. When both wheels have equal
traction, the pinion gears do not rotate on the pinion shaft
because the input force on the pinion gear is equally di­
vided betw een the tw o side gears. Consequently, the pin­
ion gears revolve with the pinion shaft, but do not rotate
around the shaft itself. The side gears, being splined to the
axle shafts and in mesh with the pinion gears, rotate the
axle shafts.
REAR AXLE 4B -3