Chris, I am not familiar with the Chevies, but I'm real sweet on the Ford 6.8L V-10.
It's a real nice engine, silky smooth and lots of torque and horsepower. My '99 E-350 - which is three head generations back - still pulls the 7000# 8-foot-box, 24-foot-long trailer nicely, at an average of 7mpg. It pulled Jeff Lawton's open trailer with my NX on it - and the back of the van FILLED with tools and equipment - literally like it wasn't there, at an average of 11 mpg. With only family in the back of the 15-passenger van, I average 14 mpg.
The latest generations of V-10 have much better heads: much freer flowing, plus more valves. Whereas the diesel grunts down low, the gasser loves to rev. Plus, when you're cruising in the paddock or backing it in at home in the middle of the night it's vewy, vwey qwuiet...
Obviously, with gas prices the way they are today, you can pick up (har-de-har) an F-350 with the 6.8L at bargain-basement prices. I'd recommend 2000 or later for the freer-flowing heads, or even 2005 or later for the increased number of intake valves.
For fuel/purchase cost reference, I've spent about $7000 on fuel for the truck over the last 3 years/30,000 miles. At best, I figure I've spent $1700 more in fuel than if I'd bought a diesel. But, I only paid $9,000 for the van, whereas a comparable diesel was averaging $15,000.
Knowing what I know now, that I'd be pulling a 24-foot enclosed, I'd likely give diesel a greater consideration. However, I think the later-gen V-10s are easily as capable as the diesel, at a significantly lower price. - GA
