First, welcome to the forum. Second, I'm not aware of any Montana that's ever had more than one pump and motor and that is in the right front compartment on the wall behind the battery. There is a hydralic ram that pushes and pulls each slide in conjuction with guides that use gears. If you crawl under the slides you should see a shiny tube and the ram will be located at the end of that above the underbelly.. On our 2010 that wasn't visible on the bedroom slide because you had to remove the plywood under the bed storage to find it.
Dick, Joyce, Diego, Picatso and Gustav
2017 3720 RL, and 2013 HC 343RL
2017 3500 Dodge Maxi DRW 4X4, Pullrite Hitch, IS, Disk Brakes, 3rd AC, Winegard Traveler, Bathroom door mod, Dometic 320, couch for desk swap, etc.