Maving worked on an Eaton 10 in my 1257 using that manual I can say it is NOT hard at all.The main thing is to have a clean bench and keep all parts very clean.
I had a shaft failure on mine was the reason I had mine apart. I got all of the part from Pete and Don Duff.
The eaton 11 is very easy also. If that happens to be what it is, the only hard part is recognizing and removing the tiny circlip that holds the bearing in the charge pump to the shaft. Took me a little head scratching and some reading glasses to find it. The seal is located behind the bearing on the 11.
My Eaton 11 hydrostat input seal is leaking too. I see by the parts list that it is part number 1724376. I checked the SKF site but the number wasn't recognized. Does anyone have a part number that can be bought at NAPA?
Crosses to ET-092999-000P on several lawn mower parts web sites as well as MTD which bought up the remains of Bolens / Troy built several years ago. Looks like it is still available from MTD for $20.86. You could try calling them at 1-800-269-6215 and see if they would give you sizes or email them - web site is www.mtdparts.com - hope this helps
Or take the seal to a good parts house like CAPS or NAPA (if you have a good one in your area) and they can probably match it up. Another option, if your near one, is a commercial bearing supply house. Most of them will have what you need.
Started by doing a google search using "1724376 seal" - it brings up several hits that you can click on (including this post on mytactorforum). If you go to mtdparts.com and click on "parts" (upper left of your screen) it will bring up part finder (lower left of screen) - enter "1724376" in the part # box and click on "go" and it brings up a smaller window with the ET-092999-000P part number as the replacement (no picture in this case so I would recommend calling them to get the sizes and compare with old one before ordering - you can use the sizes to verify or source locally if they seem correct - check lip configuration - single or double - with or without spring - etc.). It is amazing what MTD still have available - about 6 years ago I purchased 2 new gears and thrust bearings for my lawn mower deck gear box on my 1050 from a MTD dealer.
Check to see where the closest Applied industrial Technologies company is to you. Take the seal to them and they can match it. That is there specialty , bearings and seals as well as many other things. Check them out.
There was a comment about making sure your bench is clean before starting to repair the input shaft seal on the hydro unit. I am curious to know if it is possible (due to space considerations and visual access) to replace the input shaft seal on an Eaton 11 while the hydro is still on the tractor. Has anybody made this repair this way? (I would go look at my tractor but it is 60 miles away.) BTW I have a Hydro 2000 (5020H).