Navistar slaps Ford with $2 billion lawsuit
 

So if Navistar built an insufficient engine why should Ford not want to seek a better alternative ? Go Ford He said She said games

http://www.jems.com/newsreports/280994/

Here is a link to a problem Ford has been having with the new diesel engines from Navistar.
I'm an EMT and have been working in Ford Ambulances since my 1st day on the job, starting with gasoline powered engines and later diesel engines.
Starting in 2003 Ford started using a new diesel engine in van that were converted to ambulances and ambulance services have had lots of problems with those engines loosing power among other things.
I work in a 2003 Ford ambulance and have experienced problems w/ loss of power in the field, and when I was at a dealer where our ambulances are services under warrenty they had several ambulances from our company as well as several other companies, and a service tech told me that some of them had engine problems.

Now Ford has a new problem w/ Navistar engines...they won't fit in the vans or cutaway chassis's which means Ford will not be using those engines in their vans, which basically means they won't be producing vans for ambulance use.
They will however be able to produce truck based chassis that can be used for ambulance conversions.

This means that since Ford has been producing most of the ambulance chassis in use today providers will have to choose new chassis when they need to replace their ambulances.

Another reason why they are rushing to design their own Desiel. I say they team up with CAT.

Welcome to the club.