I helped another TDR member install the Rancho 9000 remote control system on his '03 3500 2-wheel drive. We mounted the gauge/control panel about half-way up on the knee bolster to the left of the steering column. He has a brake controller on the right side of the knee bolster. The air lines and wiring can be neatly tied up and aren't visible from the driver's seat and are out of the way of his knees when entering/exiting the truck.
Yep, we had problems with leaks. We used propane leak detector to find the leaks. One was at a T-connection, which was easy to repair. Two others were at the fitting that mounts to the bottom of the shock. We cleaned the fittings and the base of the shock very well and used a little grease as an aid in inserting the O-ring seal, but the fitting to shock connection still leaked. He called Rancho and they sent new fittings at no charge which were installed and no more leaks.
I'm thinking of ordering a remote controller for my truck. On an 2-wheel drive 3rd generation truck, it's difficult to adjust the front shocks. I can access the adjusting knob with only two fingers through a very space limited access hole. I haul a heavy slide in camper and like to change the settings when the camper is on the truck or driving it solo. Once we fixed the leaks on the other truck, the remote works very well.
Bill