Because way back in '83, Ford turned their nose up at Cummins because the truck would have to be modified two inches to fit the Cummins under the hood, and the Cummins was ornery and noisy, so Ford in their infinite wisdom decided to go with IH/Navistar for their quieter V8 brute that fit into the truck by modifying the engine, not the truck.
Chrysler accepted Cummins proposal and extended the nose of the truck 2" to accommodate the much coveted B 5.9 engine. The mods continued to the truck over the years to accommodate the engine, not the other way around.
Witness what happened next! Imagine if Ford had accepted Cummins' proposal. That frustration bleeds out on internet forums almost daily. :B
