Hi If you could find a low hour not worked hard, tidy tractor Cheap, Then only lightly use it you might be lucky with it. Meaning no heavy plowing or huge loads on the pto. They are basically a big heavy tractor with too much power and not strong enough transmissions to cope with the power.
This is a wish you never asked answer from a guy that fixed an 1135 that is a smaller 6 cyl turbo version using pretty much the the same transmission. I also worked in a wrecking yard taking them apart looking for good stuff for customers. some of the tractors I wrenched on had one or more of the issues below. If it has multi power the disc and drums ware and the shift slips or is slow changing. The pto clutch discs can warp or ware in the drum and they don't disengage right or slip. The splines can strip or break the couplings in the pto drive line, as its a shaft about a 1.1/8th" diameter for 150 hp. The final drive reductions can break up badly and also the splines between the rear of the gear box and drive axle can ware and strip. Ive seen some where the pump in the transmission quit and also the usual gear selector, steering, motor problems that most tractors get in high hour use.