In the process of researching my 1956 Dodge pickup for my 2001 Dakota chassis, I think two options are possible to swap a mid/late 50s Dodge pickup onto a modern chassis without altering the donot chassis wheelbase.

First is the late 90s to 2004 Durango which has a 115" WB. A long WB 50's Dodge pickup has a 116" WB. So if the 50s Dodge cab is set to align to the front wheel centerline in the fender opening, or up to 2" further back, and the fenders on the 50 box were repositioned slightly to align the fenders over the rear wheel centerline, the adjusted wheelbase of the 50s cab/box could fit on a non-modified Durango chassis with no frame length cutting/welding, possibly no driveshaft length change needed if the Durango engine does not change position to fit clear of the cab firewall. The running boards may have to repositioned slightly more rearward to mount to the rear fenders.

Second, use a short wheelbase (112") standard cab Dakota. Locate the 50s cab up to 2" further rearward on the Dakota chassis. Then reposition the fenders on the box 2" rearward, and the result is a 50 Dodge pickup wiht a 112" wheelbase. The running boards would have to move rearward a bit relative to the cab in order to bolt up to the fenders.

If the engine clears the 50s cab firewall and radiator position, I feel the front wheels centerline in the 50s front fender opening can be moved up to 2" forward to look better, and allow a slight wheelbase adjustment with no change to the chassis. I feel the stock 50s front wheel centerline in the fender opening is too far rearward to look right. That may be in part because of the old leaf spring suspension, which when fully loaded/compressed may slightly move the fron wheel centerline in the fender opening. But on a Dakota or Durango chassis, the front wheel centerline barely moves front or back from fully unloaded to fully compressed.