I happened to pass a 1943 GMC twin-axle AWD truck up on US12 in Idaho. Stopped to look; it has an interesting driveline setup.
In 2WD mode, the driveshaft drives the readmost of the two rear axles. This driveshaft is along the centrline of the vehicle.
In 4WD, the transfer case drives the front axle and the forward rear axle, via two driveshafts that are offset to the passenger side.
So it looks like 2WD mode is just the rear axle, and 4WD mode is all 3 axles.
The rearmost axle looks fairly normal. The front axle and the other rear axle are different; the left and right axle tubes are one piece with a sort of half-dish. Bolted together, the two halves contain a ring and pinion. It's not clear if there's enough room in there for a differential. Maybe n AWD mode they figure it's better to be a spool hub.
Anyone ever see a setup like this?
Cheers,
George
