I just found an old pump lying around at my Father in laws and mounted it to a homemade bracket that would bolt up to the frame members on the Gravely. Then had to buy the PTO fitting from Gravely ( strange size ). The PTO coupling had a u joint in it. I coupled that to a shaft, which I welded a piece of tube stock to that would fit snugly over the pump shaft. Then drilled a hole thru the tubing and pump input shaft and put a grade 1 bolt/shearpin thru it. then I plumbed the input and output hoses back to my logsplitter, which has the return fluid tank and the valve on it. Works great. You should be able to find a suitable pump at Northern Hydraulics for under 100.00 and I think they have the detent valve for 60 dollars or so.
It takes me about 10 or 15 minutes to remove the pump from the tractor. I then just lay the hoses with pump attached on the log splitter until I need it next.
Do pay attention to whether your PTO rotation direction and that of the pump you use. Some pumps do not care but many do care about the direction. Also I plan on upgrading my design before next splitting season, using a couple of sprockets and chain drive on the pump to increase the speed a bit. The splitter is a bit slow now because the PTO only runs about 750-1000 rpm and the pump can handle up to 3600 rpm. It still builds good pressure and splits great, just slow moving the ram, which is rather large. I think the ram came off of a full size backhoe. After I get the speed up on the pump this setup should really wham the wood.
Just kidding of course. Northern Hydraulic has these pumps also. They just would not work on a Gravely PTO, I think it is a 1 inch shaft. I believe some fo the other sub-compacts might have this size also.