Hydrostatic drive/3-speed range transmission. Only the 4041 offers this combination. Hydrostatic drive gives an infinite selection of speeds up to 10.4 mph forward, 6.2 in reverse -- controlled by one simple lever, with no need to de-clutch even when changing direction. Three-speed-range gearbox lets you select the efficient power range for any job. Limited-slip differential reduces wheel-spin under slippery conditions.
(Source: The New Size Tractor Simplicity 4041, Form 21-008, hand-dated 10-17-72, courtesy of Chris Geise)