Let me know if you had any luck. I have a 10hp Troy Bilt and can't find my manual ANYWHERE. I, too, need to know the size of the belt. Have tried 37"--too small; tried a 39"--too big; just ordered a 38"--pretty sure this will work, but I don't want to go through this "hit and miss" for every repair. Where can I get a manual? Vic in Wisconsin