Didn't know the Grant had an aircraft engine too...knew about the M10 having one. Then I look a bit... " The U.S. Army's first lineage of tanks evolved from the M1Combat Car and progressed to the M2 Light Tank, M2 Medium Tank, M3 Lee, and finally the M4 Sherman. These tanks all had rear-mounted Continental air-cooled radial aircraft engines and a front sprocket drive. "