fred42,
The motor, I believe, is a standard power window motor (maybe Ford?) and available from autoparts stores probably cheaper than the Kwikee part. I've never had to change mine, but perhaps someone here can give you some assistance with the part number. I don't know if the motor also includes the gear case as well.
The one thing I CAN tell you is to be very, very careful when working around those steps. NEVER put fingers, hands or any other appendage anywhere near the step action area UNLESS you've disconnected power to the steps and are 100% sure they cannot move. The scissor action of those bars quite possibly could sever fingers. So, be VERY careful.
Good Luck,
~Rick