'03 Chevy Duramax
 

Crew Cab, 4x4, Long Bed. I average 17.3 MPG towing a Baja 272. I average 16.9 towing DOCK HOLIDAY'S OUTLAW :D :D :D The Duramax-Allison is an awesome combo!

I am using an F-450 with the PSD for a tow rig. It is basically the same as an F-350, but with a longer bed, a higher towing capacity and most importantly, larger brakes. The best option is the second fuel tank from Transfer Flow. The truck will now carry 80 gallons of fuel. This keeps us from having to stop every few hours for a fuel fill-up. Now we can roll on and only stop when mother nature calls! :p I have had the truck for just over a year and it has been great. I use it to pull a 45' Apache and a 36' Cigarette.

I pull a 2003 Shockwave 25 Tremor (about 5500lbs) with a 2000 Toyota Tundra v8 4X4. Does a great job towing it. 18mpg non towing. 11 towing. The truck also has 107K miles on it and runs like its new.

Great responses! Keep 'em coming...
I found two trucks but the only thing I seem to have a problem with is they are only two wheel drive duallys.
One is a 2000 for F350 crew cab w/57K miles on a PSD fully loaded, and has all the ground effects added to it as well. Asking $28,900.
One other is a Dodge 2003 4 door 8 ft bed dually, Laramie package with 252 miles on it. Real nice looking truck, but no 4 wheel drive. :( Priced at 33,900
It was funny, I guy came flying in off the street, jumps out of his truck to look at it. Breaks out his cell phone about to call someone and I said, " Nice truck! Too bad it's only two wheel!" The guy hung up his phone in disbelief and said, " You gotta be kidding!" :D :D :D
We both just left disappointed thinking we found something for a bargain.....:D :D

There are some awesome setups here. Thanks Shark for the tread!!!

2001 GMC crew cab dually 8.1w/allison pulling 35 fountain on a myco trailer. I don't know which uses more gas the boat or the truck.

Love that camper shell Grandpa Justice!;)

my tow rig for the summer

another shot

95 Chevy K2500 5.7L V8 gas
pulling 85 28 Cigarette not sure of the exact weight, it does the job as long as you are not in a big rush:D