Tune for fuel mileage

[dmkhnr]

Hi,
I'm new here, and after reading about the ficm programming I feel that this is probably my best option.

2006 f350 6.0 auto 4x4 dually with 4:30 tow boss package.

I'm wanting better fuel mileage, and I understand that 2200 rpm at 65 mph isn't going to give me the mileage that a 3:73 setup would but I'm hoping for better than the current 12 mpg that I get.

I'm really not clear about what I need to do, and how long it will take. What parts do I need to send in? Can I overnight the parts and have an overnight turnaround? Please give me the full scoop on the procedure.

#2 I have an 00 7.3 4x4. It has an sct tuner with a custom tune (dp 80hp tow tune) Can I load your 80 hp economy tune as well, as I'd like to try something else.