The M-748 Truck, Bolster, 5 ton, 6x6 is part of the G-744 (or M-39) series of 5 ton 6x6 trucks. More information about the history, model numbers, and configurations of the M39-series of trucks is on the linked page.
The M748 Truck, Bolster, 5 Ton, 6x6 was produced with and without winch in -A1 and -A2 variants. The truck was 314 1/4 inches long, 121 inches in height, and 98 inches wide.
This vehicle is also called Truck, Logging, M748.
M748 Truck, Bolster, 5 Ton, 6x6 from TM 43-0001-31, June 1985, Page 4-141.