The M5 13 ton High Speed Tractor was a World War II era artillery tractor that was used by the US Army from 1942 to tow medium field artillery pieces.
M5 tractor
M5 tractor in Korea.
M5 on May parade, Ljubljana 1961
An artillery tractor, also referred to as a gun tractor, is a specialized heavy-duty form of tractor unit used to tow artillery pieces of varying weights and calibres. It may be wheeled, tracked, or half-tracked.
Wheeled British WWII Scammell Pioneer towing an 8-inch howitzer
Tracked Finnish WWII Komsomolets (captured from USSR)
Half-tracked German Sd.Kfz. 7 towing an 8.8cm Flak
German RSO artillery tractor towing 105 mm howitzer, Albania, 1943