I thinkong about buying a `08 Ford F-350 diesel or a `08 Dodge Ram 3500 diesel. I want to know what one is better for ranch work & what problems they have.

Most ranchers in Texas go with the F-350. I've worked on them and they are fine work horses. They are definitely tough and will last and last, if you properly maintain them. Ford cabs (creature comforts) and bodies are better and preferred. Dodge really has a problem with dashboards cracking up big time--a constant source of problems. Many people, however, buy the Dodges for the Cummins diesel engine. If they still offer a lifetime warranty on the engine and drivetrain, that's pretty powerful. That assumes Chrysler survives long-term. In the final analysis, it boils down to personal preferences and price. I've never met a truck that I didn't love. Buy the Service Manual, if you plan on keeping the truck for a long time. As a generalization, ranchers buy Fords.. . "urban cowboys" buy Dodges.

It is more a dealer availability than anything else in most parts of the country. Any of the newer diesels that utilize a DPF (diesel particulate filter) system will have problems if left idling for prolonged periods. Chrysler has never offered a lifetime warranty on the diesel motors, contrary to what some might say.
I am currently driving a Dodge and really like it. Did not even consider a Ford for several reasons. Pick the one that offers the best in dealer support. Bottom line, remember that a V8 will have about 30% more parts than an I6 Cummins. No matter what, I would look for a used pre 07 diesel for your intended use.

I doubt Chrysler will still be running by 2010. I would go with the Ford, it does what it says on the can. A Dodge looks pretty, more for weekend workers.