Model Variants (Including Prototypes)
T49 GMC - Initial Prototype; 57mm main gun; torsion bar suspension system.
T67 GMC - Second Prototype; 75mm main gun
T70 GMC - Third Prototype; 76.2mm main gun
M18 GMC "Hellcat" - Base Series Production Designation.
M39 - High-speed APC or supply carrier platform based on the T41 turret-less design; 650 examples produced.
T41 - Turret-less M6 anti-tank gun carrier / troop carrier.
T41E1 - Fast Reconnaissance Vehicle based on the T41 turret-less design.
Heavy Artillery Tractor - Proposed Variant
Mobile Command and Communications Post Vehicle - Proposed Variant.
T65 Flame Tank - Flamethrower conversion model; revised upper hull for incorporation of flame projector.
T88 Howitzer Motor Carriage - Experimental 105mm howitzer platform; never produced.
90mm CMGC - Cannon Motor Gun Carriage fitting 90mm main gun; never produced.
T86 - Proposed Amphibious Howitzer Tank; track propelled.
T86E1 - Proposed Amphibious Howitzer Tank; propellers used for propulsion.
T87 - Proposed Amphibious Howitzer Tank; 105mm T12 gun; track propelled.