First, this is a joke, right? A gas furnace in the living room, no duct, horizontal vent, dead mice in the blower, vegetable oil lube?
There are so many red flags here, the best thing you could do is call the fire department and have them condemn this thing. There are so many issues regarding carbon monoxide, fire ( how is the gas piped to this thing?) you could get this lady killed.
As far as your specific question, the GE 5KCP39-series motors are all proprietary parts for the manufacturer, in this case goodman. Is there a capacitor on the motor? No way of telling if this is a multispeed or variable speed motor. If the furnace is old, it may not be either.