Hey I get a lot of info from this site and almost never post. So I figure I'd contribute a trick I learned in my dads Toyota only wrecking yard ripping down 4runners for him.

Thing is that both drive side door motors are essentially the same as the tailgate motor, I've even gotten the passenger side motors to work but they don't fit as well. Good thing is that the driver door in particular works great in the tailgate because it is typically the strongest motor in the truck. Also, another trick is that it is actually really easy to swap gears between motors if you have a good motor with crappy gears and another dead motor with good gears.

Anyway Hope this helps someone at a U-pull where all the tailgate motors are gone or priced high as a rare item(if they even work).
Sorry for a lack of pictures i'll try to get some later.