My tractor's a bit different than yours. It is however also made by MTD. I've been trying to get there pubs/manual dept on the phone for days with no luck. I did get tech support which was a great help. He couldn't ID my model exactly because the plate on the tractor was damaged, but going by the information I did have he was able to figure out enough to tell me the manual I need is 770-5239A. I was very impressed.
Take care, and thanks for the assistance.