M5 high speed tractor, built by International Harvester, not AMC
By high speed, they mean 35MPH, 16,000 lb cargo capacity, 20,000lb tow capacity.
The tracks and drive sprockets and other parts are off the M-3/M-5 light tanks.
Eight crew, used to tow 155mm or 4.5" guns.
Six cylinder inline, 572cu in engine with 235 hp. (6.5 to 1 compression

)
Range, 125 miles.
Speed, 35mph
Weight, 28,600lbs
Guns, in addition to towed gun, one .50 Browning mg, M1's and carbines for the crew.