Kingcreek -
I have the same tractor and was experiencing a leak at the PTO shaft, so tackled this project last weekend. Ordered the PTO seal from the local dealer (forgot to order a gasket but I may have gotten away with re-using the old one). Looked around here and elsewhere for tips and dug in.
1. Drain at least 4 gal of existing hydraulic fluid.
2. Raise and block rear end if you want to drain less fluid if you have a way to safely do so.
3. Remove the four bolds holding on the exterior plate
4. Separate the rear plate from the rear housing and pull out the PTO shaft.
5. Inner shaft is splined and attached to a matching shaft internally with a coupler - the coupler may remain on the internal shaft or come out with the shaft that you remove.
6. Once out, you'll need to remove a large snap ring (about 3") so use a good strong snap right plier and it will be SO much easier to remove
7. After removing the snap ring, use a rubber mallet to tap the PTO shaft through the outer housing (from the outside toward the inside)
8. The PTO shaft seal will remain in the outer housing and can now be removed and replaced with the new one - make sure of the orientation so that you install the new one properly in the same direction as the old one (open end toward the bearings)
9. With the old seal removed, clean everything and reassemble.
10. Replace the shaft through the new seal, re-install the snap ring and replace into the rear housing.
Entire process took me several hours, but I could probably repeat it now in 30 minutes (although I hope I never need to do so).