Have two Hydro 84 MFWD tractors and for loader work they are great. Both motors have been O/Hed. One was bad head gasket plus wore out and 2nd was getting coolant in the oil. Have no idea how many hours are on either tractor as both were bought used. Parts have not been a problem. Have been able to get parts for everything that I have repaired on them so far. Have had no issues with hyd's. Use hytran for fluid. I would not hesitate to buy another of this series tractor. 

Might add the diesel pump shop did tell me that parts are getting harder for them to find for the injection pump. So I would make sure it starts correctly and use clean fuel and change the filters often.

Edited to add comment about fuel pump.