The difference between the M998 and M998A1 cargo/troop carriers and the M1097, M1097A1, M1097A2, and M1123 heavy variant cargo/troop carriers is that the M1097, M1097A1, M1097A2, and M1123 are specifically designed to accommodate a higher payload capacity.

The M1123 models, like the M1097A2 models, have new bumpers, which make the vehicles slightly longer. A 9,000 lb winch is also available for the M1123 and M1097A2 models as an option.

These differences affect approach angle, special winch-assisted Operations, vehicle length, vehicle weight, and shipping dimensions. It does not affect the basic purpose, performance, or special limitations of the vehicles.

The M1123 heavy variant cargo/troop carriers are used to transport equipment, materials, and/or personnel. The heavy variant troop carrier is capable of transporting a two-man crew and eight passengers. The heavy variant cargo carrier is capable of transporting a payload (including crew) of 4,400 pounds (1,998 kilograms). The M1123 use a troop seat kit for troop transport operations, a 200 ampere umbilical power cable to power shelter equipment, and stowage racks for ammunition and equipment. For higher payload capacity, the M1123 are equipped with a reinforced frame, crossmembers, lifting shackles, heavy-duty rear springs, shock absorbers, reinforced control arms, heavy-duty tires and rims, and a transfer case and differential with a modified gear ratio.

Fully-loaded M1123 heavy variant cargo/troop carriers will climb road grades as steep as 60% (31°) and traverse a side slope of up to 40% (22°). The vehicle fords hard bottom water crossing up to 30 inches (76 centimeters) without a deep water fording kit and 60 inches (152 centimeters) with the kit.