What are the 920's used for? line haul?
The M915's were the line haul tractors of that time. They had three axles, a 400 Cummings, a CAT semi-automatic transmission and no front wheel drive. The two rear axles were just like a commercial rig with a power divider. The early ones were made by AMC.
I had the dubious honor of driving one from Fort Benning, Ga. to the National Training Center in Cal.
The M916 was a three axle tractor with front wheel drive. It was used for medium hauling in rough terrain. I put a lot of miles on one in the ordnance unit I was in. We used it to haul small dozers and 6k and 10k forklifts. Same engine and tranny as the 915. Also orginally made by AMC.
The M920's were mostly in engineer units and used to haul heavy construction equipment. Some maintenence units had them for recovery and to haul their own heavy stuff. Ditto on engine/tranny and AMC.