New Ram Mega 3500 DRW 4wd, old 5er....

I have a 2012 Ram 3500, had the same issue with my 5er. I first set my pin box and my B & W Companion at the positions that gave me the most bed clearance. I also removed those three spacers from under the leaf springs on the truck, and placed them on top of the leaf springs. This allowed me to use the same hardware. Job took me about an hour. You need a couple of jack stands, and at least a floor jack. It would help if you had a second jack also. You will need to jack the truck up, support the frame, and then lower the axle down a little. Spray some penetrating oil on the bolts before you start. You will lower the truck about 1 1/2" in the rear by doing this. It will not affect your payload capacity in any way. If these things don't give you enough clearance, the next step would be to flip the axles, or add spacers if the axles are already under the springs. You want to keep the trailer as low as you can, keeping the center of gravity as low as possible. I once looked at a used 5er that I loved and wanted, but there was no way it would fit my truck without flipping the axles and adding huge spacers. Wouldn't have been safe, so I passed on it. Do some measurements, check out the mounting options on your pinbox and your hitch. Moving the spacers on the truck springs will lower it 1 1/2" on top of whatever you gain on the others. It worked for me, my '09 Mountaineer tows level, and I have 6 1/2" clearance on the bed rails. Good Luck, hope this helps.