I highly recommend Preferred Doors. I recently purchased a gear and pulley replacement set for my 20 year old Craftsman belt drive 1/2 HP opener. The parts were very reasonably priced and of excellent quality. What set this purchase apart from others was that it included everything needed to do the job, gears, clips, bushings, spacers, grease... They also included very thorough details on how to replace the parts, reset the limit switches test the opener and reset the wireless openers.
Had the part for an old sears opener that broke. Fit perfectly. Bought an extra one for next time. The one problem was waiting for USPS to deliver. Thanks for the quick response and would buy from again.