I have a peerless transaxle with a 5/8" bore by 9" wide and 1" high pulley. I'm trying to find one a little smaller but same bore and height to add a little speed. It's got a flat belt. Does anyone have any ideas?

You might try mcmaster Carr, i dont know if they would have that but they have a lot of stuff. There site is www.mcmaster.com
ben

Or farm supply stores.. not TSC but like a Case or Massey dealer, or other larger equipment dealers.