US Army M149 or equivalent. The M149-series water trailer is designed to be towed by 2- and 5-ton vehicles. It has a 400-gallon capacity and is available with either a fiberglass or stainless steel ta... US Army M149 or equivalent. The M149-series water trailer is designed to be towed by 2- and 5-ton vehicles. It has a 400-gallon capacity and is available with either a fiberglass or stainless steel tank. QTY 2x. One-time purchase. Warranty required.