Just make sure the transmission fluid gets changed, every 300-400 hours and use Super UDT. GST is an automated 12 speed gear transmission with a forward reverse wet shuttle clutch, do not need to use the foot clutch for any shifting.
If treated well that is a very good tractor and can pull all day without any of the concerns one would have with a hydro overheating.
Check and see if the front drive shaft seal is leaking or has been replaced, only real problem I have heard on that series.
David