This 7711 has both end pieces. The 540, (6 spline), is attached on rear of tractor. The 1000, (21 spline), is in a recessed hole in floor board under the pto speed selector lever. Each end piece has two ends. One end has the splines and the other end, which is inserted into the rear of tractor or the recess in the floor board, has a shaft with two notches in the end and a groove down the side. Which ever one is inserted in the floor has to be turned about 45 deg. and then pulled out to remove. Also the one that is inserted in the floor is actually what the lever turns to select speed. The lever is actually just a cap that fits over the end piece. If you have the 1000 pto end piece in the floor recess, it prevents you from selecting 1000 pto speed. If you have the 540 pto end piece in the floor recess, it prevents you from selecting 540 pto speed. Therefore the other end piece would be mounted on rear of tractor for use. I can remove the 1000 (21 spline) from the floor recess, but I'm trying to figure out how to remove the 540 (6 spline) from the rear of tractor. I know this cant be difficult because its made to interchange. Im just trying to figure out how to do it. Most tractors , you just pull a clip by the end piece, pull it out, flip it around , put it back in, and put clip back in place. 21 spline on one end and 6 spline on the other. Thomas