I think you're out of luck on OEM parts for that unit. I've tried to look at this question as to how it would be applicable to anyone's unit. On the nameplate, you're given the horsepower and you know it's 220v; the only question is what RPM it needs to be. I think it's reasonable to assume that if it's a 1/6hp motor, it's not any faster than 1, 200 RPM. It is possible that it's even slower though... (that's why I just ask the guy at the store).
I'm reasonably sure what you'd need if it does fail is a 1/6hp ~1, 200 rpm motor. (I don't think you can go wrong using a 1/3hp motor.) If whatever's in there ran fine for years, I'd be using a direct replacement of the existing one's specs.
Personally, I never ask for OEM parts (it's not like Rheem winds their own motors anyway). I get the $100 version and go on with life. I go to the parts store, plop the old one on the table and say gimme. Considering that the OEM motor failed less than nine years into service, why would you bother? :) Just run it into the ground: Don't fix it if it ain't broke.
Six-pole motors run at 1, 200 rpm unloaded (7, 200 Ã· 6) and between 1, 050 and 1, 175 rpm loaded. They are often used for air-handling equipment, direct-drive applications, window fans, furnace blowers, room air conditioners, heat pumps, and other equipment where the relatively slower motor speed makes for quieter operation. –How to Determine Speed for an Ac Induction Motor, achrnews.com
Example: A 20-inch, 24-degree pitch fan blade operating at 1, 140 rpm will require a 1/6 hp motor for proper motor and system performance. That same blade operating at 1, 725 rpm will require a 1/2 hp rated motor. The blade is designed to work in both applications; however, the increase in operating speed has a direct impact on the hp requirements. Operating this fan blade at the higher rpm requires a minimum 1/2 hp motor. Less than 1/2 hp will most likely cause the motor to operate in an overload condition. –Stop Blowing Hot Air, achrnews.com