Neither company has a proper "world truck" to build on.
I don't know if I agree with that at all in 2011. This is a map of
only their manufacturing plants worldwide:
http://corporate.ford.com/about-ford/global-operations
They are manufacturing Fords on all of the 6 available continents. That is just manufacturing facilities, not parts and service stations. I tend to think that I could get Ford parts sent to 99% of places where Mercedes ships to. Satellite internet is global as well. If you have internet service, you have access to a factory trained mechanic. Sitting at is home in the middle of Iowa. Drinking a beer. Walking me, step, by step, through a diagnosis and repair procedure. On a forum about Ford trucks or Ford diesels, like Expo.
While Mercedes is certainly better established, I believe that with the internet, better global shiping and a world that grows smaller every day, I can get Ford parts pretty much anywhere I could get Mercedes parts and also with the Net, I have access to Ford factory trained mechanics, willing to help me for free.
The internet is pervasive and powerful. It makes Ford platforms a more usable world wide expo platform. Doesn't hurt that in the last couple decades Ford has done a good job establishing a global footprint and presence.
Maybe I am a fool (wouldn't be the first time), but I wouldn't hesitate to take a Ford F Series or E Series (Class 3 and above) on any continent (excluding Antartica) for fear of being unable to obtain parts or service knowledge. And I would definitely take a Ford worldwide before a Chevy or Dodge. But, I am a bit biased as I have a Class 3 E-350 Cutaway chassis I am going to start on in about 6 months. I have given this quite a bit of thought, and again, ignorance is bliss and perhaps I am a fool, but I am going to scrap the 460 and convert to diesel, using the diesel powerplant that works best for my needs, be it the new Ford, an International, Cummins, etc. - any popular US engine (the might be a fool part with any popular US engine), I can get parts for worldwide, as well as worldwide service help from a factory trained mechanic via net.
Not trying to be offensive, so feel free to point out any flaws in my thinking.