FWIW - In addition to CJoe's comment and if you haven't figured it out yet - I just did this myself - try holding shaft and twisting collar while pushing it towards the long end of the shaft. There are two o-rings in the collar which were really tight on mine. I sprayed some PB blaster on both sides in case it was rusted. Be careful tapping it as the flange must be straight. Once mine spun, I got the clip out and pushed the collar back out towards the front of the shaft.
Upon reassembly ...the c clip goes on which groove ?
It seems to determine where the collar sits on shaft...i have 3 grooves? Shop manuals dont help..they dont even show the c clip...
The c-clip is a redesign since the manuals were printed. Originally there were 3 o-rings. The clip goes in the forward most [PTO end] groove. O-rings in the other 2.