Well had a PacBrake air powered exhaust brake on our 2001 Ram 2500, got real use to having air where the truck was!
Jump forward to the new 2016 Ram 3500 DRW with factory exhaust brake, NO Air!! :S
Well hunted down a VIAIR system constant duty at 100 psi, and max pressure of 150 psi, with a 2.5 gallon tank. I chose to mount the tank and compressor inside the side panel of the bed on the passenger side.
I managed to do this install with only drilling a couple small screw holes in the new truck.
Bracket to support tank under bed, used bed mounting bolts, and two more unused 12mm-1.75 holes to attach.Tank in place and compressor mounting bracket in place, clamped to box frame.Engine bay air outlet.Air outlet in bed.