Re: New F350 SuperDuty
Just so you know the 6.2L has a reduced output on models with GVWR at 10K or higher. I know Gm knocks it from 360hp to 323hp on their 6.0L V8 gas engine for greater long term durability; torque remains the same.
If you get enough snow, it might warrant the locker. If you do a lot of tight turning and the climate doesn't get very cold, avoid the locker, as it can eat through tires, more so with a dual real wheel. I'd also avoid electronic shift on the fly. A replacement solenoid can fetch several hundred dollars and it can fail anytime, 40K, 50K 100K 200K. It's a guessing game. I'd stick with the shift-it-yourself 4wd.
If you don't plan on putting anything on the front, such as a snowplow, don't get the spring upgrade package - it will make the ride quite jarring when not carrying or pulling anything.
I'd stick with the 3.73 gears. The 6 speed has the flexibility where unless you need the maximum towing capabilities of the truck (5th wheel), the 4.30 gears isn't necessary. If you do a lot of empty highway miles, the 3.73 will be plenty adequate.
Even with the 3.73 gears, I wouldn't expect anything higher then 15-16mpg highway at 60mph.
Dealers hate sitting on vehicles. As CatSkinner mentioned, bid low. Buying new can have more perks if you know how to talk. When I bought my Taurus back in '99, I got the sales manager to include services at no charge for the duration of the warranty. The car was also a demo model which I haggled down in price considerably.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!