Looks like clutch material but its hard to see real good. Personally I would rebuild the one you have or have it rebuilt at a hydraulic shop or dealership, buying things like this used can be a real crap shoot, its a lot of work to swap it out and then find out its bad too.
Just my opinion and experience as a diesel tech for over 20 years and having seen guys go through this too many times trying to save a buck by buying a used part as critical as a hydro.
Thanks for the reply W & F , So I have checked on a replacement hydro from dealer and the are no longer available and parts are getting scarce. And they won't deal with rebuilding one. I checked my local kubota dealer and a couple others and same thing. Some parts are available like charge pump gearotors but for 3,000 dollars, but without tearing into it I really don't know!
I followed a link someone posted from an outfit out of Kentucky for a used one for 1500 and a 45 day garuntee,
Kind of wondering If I should gamble 150 bucks on new filters and oil, and see if I can get my ground speed back. Like I posted earlier I pulled the strainer last time I changed fluid but just cleaned it on the outside so who knows how long the gunk had been in thier.
The way the tractor runs now is I'm only getting about 50 percent speed when first taking off and it just deminishes from thier. Some times to get it moving again I have to replenish the hydro supply by lowering the bucket of letting it set for a minute to build pressure in the hydro again. So I really don't know if that strainer was causing much of s flow issue or not.