The M-925 Truck, Cargo, 5-ton, 6x6 is part of the M-939 Series of 5 ton 6x6 trucks. Details of the history, model numbers, and configurations of the M939-series of trucks are on the linked page.
The M925 is a dropside cargo truck of standard wheelbase. The M923 is the same vehicle without a winch. USMC M925 (and M923) cargo trucks had an updated cargo body with five drop sections (one rear, two on each side), compatible with ISO containers.
Marines use an M925A2 5-ton 6x6 cargo truck from Alpha Battery, Camp Pendleton, CA, to tow an M198 155mm Medium Howitzer to its firing position, Exercise Kernel Blitz '97, Marine Corps Air Ground Combat Center, 29 Palms, CA, 27 June 1997.
Senior MSGT Christi Hayburn on the running board of an M925A2 5-ton 6x6 cargo truck showing Senior Airman Daxton Newberry where to station his equipment during Tactical Fighter Weaponry 2001, Tranum, Denmark, 15 August 2001.
M-923 Truck, Cargo 5 Ton 6x6 drives into the surf from the utility landing craft LCU-1649 during Exercise Solid Shield '85, Onslow Beach, Marine Corps Base, Camp Lejeune, NC, June 1985.