Ford and Navistar had been collaborating since 2001. Nav had the factory, Ford had the money, and they each got their own brand of medium-duty commercial trucks out of the deal. But Ford's broken off to go proprietary, and just like that former friends become rivals.

The joint venture, "Blue Diamond Truck Company, LLC," produced Class 6 and 7 Medium Duty commercial trucks (bigger than a pickup, smaller than a semi-truck) sold as Internationals by Navistar and F-650s and F-750s by Ford. Navistar made the bodies and engines, each company did their own thing with cabs and design.

The deal effectively made Ford into Navistar's biggest customer.

For 2015, Ford's next-gen F-650s and F-750s will be , with Power Stroke diesel engines from the company's plant in Mexico and no Navistar components whatsoever.

Ford is moving production of its F-65o and F-750 commercial trucks from Mexico to the United States

It's going to be a real scramble for market share as Ford tries to build on the presence they've established in the commercial truck market through Navistar while making them their bitch at the same time.

Ford's new offerings look strong, but Navistar still has a big lineup of Cummins ISB engines in their International trucks which gives them a pretty deep following.

reports Navistar is taking heavy financial losses this year vis the Wall Street Journal, but if they're smart they'll turn the split with Ford into an opportunity to strengthen their own brand name.

Power Stoke and Cummins are both names with substantial weight in the diesel world, and once the drop they'll have a whole new market to fight over. I'll be curious to see what kind of impact the commercial-level popularity of one over the other has in the light-duty market, if any.

Ford just announced a new version of some of the vehicles that are most likely to affect our lives…

Would you be willing to try out Ford's Power Stroke in a professional aapplication, or would you rather stick to the time-tested Cummins in an International?

Images: Navistar & Ford