The PTO drive shaft came already mounted to a slip clutch on the rotary cutter. The drive shaft slid out ~16" or so not sure I'll measure in the morning . I'll try taking the two halves apart if I can't find my calipers. Yes the end of the tractor PTO shaft is tapered and the drive shaft doesn't seem to make it past that either which is what lead me to think they are not right together. I can turn the tractor PTO shaft CCW enough that if they wanted to go together they should be able too. The drive shaft cam with two chain one on each end. the one was in attached to the mower already, the other was hanging partly in a little baggy. I'll put some marker on the drive PTO to measure the distance travel while raising/lowering it. I only hope I don't have to cut anything. I can but its not something I am looking forward to.