Chances are if you enter the model of your quickee step into google one of the search results will get you to the right window motor.
Or if you feel like taking the motor out there's probably a Ford part number of it somewhere. You might even be able to see it without removing the motor.
At least one person here just took the motor to the local Napa Auto and they found it for him.
Those poor steps & motors are sure in a hostile environment. I got to remember to clean & lube mine soon.
Happy hunting and good luck.