I can only tell you how our '16 39MB is setup: When looking toward the hydraulic pump I have a block with two thumb screw valves, the one on the curb side controls the curb side slide, the road side valve controls the road side slide. Now you have to follow the hydraulic line over to the road side wall where there are two solenoid valves, one for each of the two main slides. I don't recall which is which, but it's pretty easy following the lines from the thumb screw valve block to the solenoids.
But this disclaimer: There is no guarantee that each model is the same.
Michelle & Ann
2018 Chevy 3500HD Crew Cab High Country DRW, D/A, 2016 RW39MB, Dual ACs, Auto Level, Auto Sat Dish, Stack W/D, King Sleep #, 17.5" Sailuns w/Disc, MORryde IS & Pin, Comfort Ride Hitch, 5.5 Onan, Res Fridge & Induction Cook Top