The Dodge lifetime warranty does not apply to diesels, high performance vehicles (SRT), or fleet vehicles. Therefore, if you get a diesel ram you still get only the 3/36,000 warranty, unless you buy an extended warranty.

Personally, for a ~14,000 load I would look at the 3500. It's better to have a vehicle that can handle more than what you're hauling than one that is overloaded, even a little. It will be noticeably more stable and comfortable to tow with the larger truck.

Even so, definitely drive both the 2500 and the 3500. Don't let the dealer talk you into something without trying out the alternatives.

As far as the Ford goes, they had problems with the regeneration process (it would shoot flames out the exhaust). This was caused by a combination of bad injectors and a computer error. It has since been rectified (personally though, I believe the bad injectors came from people trying to use low sulfur diesel in an engine that requires ultra low sulfur). It doesn't matter which diesel you go with as they now all have a diesel particulate filter, that's part of the new 2007 emissions. New technology needs a little teething time.