IMHO the 2500 should be a single rear tire and the 3500 is the dual. I beleive this is how it was many many years ago.
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'08 6.7L 4 door 4x4 LB. Mineral gray. Lorenz bilstein leveling kit with DP leafs. SRT hood. 5K HID's
5" TBE, EGR & cooler delete, Edge w/ATT, CAI, Airdog 150, Frants oil filter. Smarty S-67ME 120HP fireball injectors.ARP 425 studs to 135#, II 64/71 Stage 2 VGT Turbo