Have you contacted Atwood? They're pretty good about responding and letting you know what parts will work in your furnace
. I won't say that they necessarily give correct information...but they will respond.
Be prepared to be out of luck, though. At least with my 1991 Atwood furnace
, even though they make a furnace in the exact size and dimensions, the blower motor is not compatible, according to people. I'm not convinced, exactly, but I'm also not willing to experiment too much on my furnace.
Unfortunately you won't find many people around here who have dug into their furnace. Try Atwood customer service, and if that doesn't get you anywhere...it may be time for a new one. Atwood seems to be pretty high quality, but you pay for it...
You're sure it's the motor?