There are two primary improvements to the Super Duty's driving characteristics, in what has always been a competitive vehicle: the diesel engine is all-new and the rear springs' forward perch has been moved forward eight inches. You may not care about spring location, but that eight inches gives a much better ride for the same load, so you can drive an empty dually without looking like a bobblehead doll.

While 20-inch wheels may look better, they tend to degrade ride comfort so if your driving involves marginal roads, or no roads at all, better to stick with the standard size. Regardless of hype, no heavy-duty pickup rides like a car, and the Super Duty is no different. The only instance in which a competitor might hold an advantage is with GM full-size 4WD steering precision or ride comfort, a tradeoff many happily accept to get the Ford's solid front axle design often considered superior in durability.

If you're not accustomed to driving full-size pickups you may find yourself trapped in a strip mall feeling unable to escape. Otherwise you'll find the Super Duty has no obvious drawbacks in maneuverability for such a behemoth, and the cut-down front windows, mirrors, and clear bodywork edges give good indication of presence relative to surroundings. If you haven't anything heavy to carry or tow, a Super Duty's capabilities will far exceed your requirements.

The word handling isn't ascribed to HD pickups as much as control is, and the Super Duty feels comfortable even with heavy loads. Brakes don't stand out as good or bad, and four-ton trucks never stop like cars, but the Tow Command system can't be beaten; the Super Duty does not offer a factory exhaust brake option like the Dodge Cummins, a feature equally useful on long hauls.

The 6.4-liter diesel engine is all-new for 2008, with just two parts shared with the previous 6-liter diesel. It is much quieter, cleaner (the exhaust may be cleaner than the air going in, in some cities) and has likely given up a few percentage points in fuel economy because of the added output and heavier trucks. Apart from the speed with which it barrels up hills and the probable 10 percent to 40 percent better fuel mileage, it's not noticeably different than the gas engines. Note that on F-450, unless you get an automatic and 4.30:1 axle ratio, the diesel is de-rated to 325 hp and 600 lb-ft of torque. Also note that the five-speed automatic transmission falls one gear short of GM and Dodge's six-speed automatics.

The standard 5.4-liter V8 is the cost leader, and it's a good choice if you don't plan on towing anything more than 5,000 pounds over relatively rolling countryside. Those who might carry a full load of tools or cement and tow a trailer but not drive a lot of miles should consider the stronger V10. For maximum towing or high-mileage service, the diesel can't be beat, and neither can its price tag, around $6,900.

Changes between the F-250 and F-350 SRW are essentially limited to the 350 capable of carrying another 1,000 pounds. The F-350 DRW goes another step further in payload and frequently more important, much better trailer towing (or camper carrying) stability. The max tow rating on some F-350 DRW is more than 18,000 pounds, but remember those ratings are given with a nearly empty, low-optioned truck.

For 2008, the Super Duty adds an F-450 model, a truck that takes a medium-duty chassis cab and adds a pickup box much like aftermarket firms have been doing for years for affluent trailer pullers. An F-450 can carry as much as 6,120 pounds (the weight of an F-250 regular cab) and tow as much as 24,500 pounds, but still enjoy pickup perks like a usable bed, no stops at roadside scales, and a factory warranty. Just make sure your driver's license can handle that load, too.

You can spot an F-450 by the 10-lug, 19.5-inch wheels and huge rear differential. The tires alone contribute to a firmer ride, and the added rolling and fixed mass bring slight increases in acceleration time and stopping distance. If you have a big trailer or a lead-like load this is the way to go, if not, you really don't want an F-450.