LVT-4: Amphibious cargo and troop carrier used by the United States during WW2. It floats, carries six passengers, and sports two M2 .50 caliber machine guns. It can replace any land or water vehicle.
LVT(A)-1: The LVT adapted into an amphibious tank, featuring a 37mm gun and coaxial .30 caliber machine gun in a turret taken from the M3 Stuart and two machine gunners seated aft. They're supposed to have .30 cals but w/e.