The M33 was based on the Vehicle, Tank Recovery, T2 (standardized as the M31 TRV) which was derived from the M-3 Lee Medium Tank. In 1943-1944, the M31 TRV was being replaced by the M32 Tank Recovery Vehicle, based on the M4 Sherman tank. Over 100 of the M31 TRVs were converted to the M33 prime mover.
