Did he go through the backend thoroughly?
Hi lo seals replacement,new charge pump??
Syncros in the gearbox??
My 3650 had a full gearbox rebuild including new bearings ,brought about by the failure of a small cage bearing.
Literally every nut and bolt from the pto shaft to the front HYD pump has been apart and redone due to failures,the engine rebuild was only like a starter for a 7 course meal.
My tractor has a lot of hours done but so do most of them.
I still like it for some reason that defys logic.my teenage sons think it's the dogs danglies to drive,they are right too but they don't have the emotional and financial scars it has left on me!
Still don't look at it.in action without a smile though.