Originally Posted by gmctd
The 3500HD is actually the 4500 chassis, straight front axle and Rockwell differential, with a lifted body, created for the proposed Caterpillar Diesel - GM couldn't come up with a suitable automatic trans or manual trans for the big six so the deal fell thru.
You get a 10-lug - the 19"wheels have 5 blocked off - 4500 in 3500 garb, which does not require a CDL, and avoids commercial taxing.
Wheelbase is easily altered by unbolting the frame rear section and sliding it in or out of the mid-section rails, and the frame is thicker and much heavier than the 3500 frame
The 3500HD is identifiable by the 6" extension below the grille with the large vinyl fender flares, and the large 5-bolt lug pattern of the 19" wheels.