The drive shaft doesn't 'just pull off'. /forums/images/graemlins/wink.gif
When removing, there is a ring keeper that has to be slid forward, and then the drive shaft will slide off, also forward.
Same deal when installing. Slide the PTO onto the splines just a fraction of an inch, slide the ring keeper 'forward', and then slide the PTO shaft 'rearward'. Can be a tricky maneuver to do this with one hand. Reaching in under the axle from the rear of the tractor is the easiest way to do this one-handed. Sometimes, the 'ring' is tight, from not being removed and dirt/grease binding it up. I have managed to free it up with a small pry bar or screwdriver, being careful not to damage the coupling.
No manual? Should have been one along with it to maintain it at the Church. Someone at the Church should be familiar with using this machine, and should be able to give you some pointers, safety and otherwise. Also, stopping off at the dealer for some tips would be good.
As far as the box blade, I think the 455 will take a Cat O 3pt, which may not fit the box blade. Finding a 3pt for it might be a challenge too.