I'm just looking at the 2004 brochure and the difference in payload between the two --A difference of only130 lbs? I find that hard to believe.
RAM 3500 QC 4x4 Hemi = 4750 lbs, Cummins = 4660 difference = 90lbs (the 130 lb number is for a 4x2).
OTOH if I look at a RAM 2500 QC 4x4 Hemi = 2760, Cummins = 2270 difference = 490 lbs.
Now I'm just confused since I thought all 3500s had the same GVW. Maybe not (and i'ts not listed. )