look for the usual things.
Look for water in the oil. if overheated the heads could be cracked. Having wet sleeves the could be leaking. Some never ever leak and i've seen some that leaked after the rad/block was drained.
Look for major leaks around the steering gear box especially above the wheels. Narrow front take more abuse on the bearings and can wipe the seals our. Gear boxes are $40 to $300 used.
Fenders are notorious to rust.. not a huge deal.. they still drive the same.
Driving: make sure the Direct drive engages well with a good snap. GReat tractors. I like mine ... good luck