First off, how misleading was the seller?
Next, I agree that you can't do much better than the Kohler K for this application.
Also, I wouldn't jump to buy another trans. Check and see how much wear it has. It may only need cleaned with kerosene and refilled with trans fluid. If it needs rebuilt, that's not a bad job and is preferable to buying another worn trans.
The seller (a friend) was not misleading. I saw the tractor in his yard and asked how much. He said a grand and one trans is stuck in gear. I said ok. I took the cover off the bad tranny and the main shaft has play in the front end. Maybe I can just rebuild it with new bearings and seals. Not sure yet.