3.5 Eco or 5.0 V8 with which rear end
 

I am looking for a crew cab to haul a 1500 lb boat approx 200 miles 2 times a month. I like the idea of the fuel economy of a 3.5 Eco with a 3.15 rear end ratio, but not sure if I should go with something like a 3.31 or 3.55 rear end. Or if the 5.0 V8 with a 3.31 or 3.55 would work better. If I choose to go with the 3.31 or 3.55 ratios want I pay for it with fewer mpg? I have a 3000 lb tractor that I may need to haul once every couple years. Additionally, this truck will be my ride to work plus general use 300 miles weekly.

3.15's all the way if you decide on the EB. I haul 5 times that weight on occasion and have no problems. I lock out 6th gear and it never shifts out of 5th, even on hills. The fuel mileage will be the best with the 3.15's when not towing.

Thanks for your comments.

Follow up...
 

Took a 600 mile round trip today from central Missouri down through the Ozark hills/mountains to Jonesborough, Arkansas and back to pick up a truck my son bought on Ebay. Going down I just had my 18' flatbed car hauler that weighs in at about 2000 lbs. Got 18.1 mpg calculated with a heavy cross wind. Pulled all the way in 6th gear. On the way back with the Ranger loaded aboard I got 14.2 bucking a strong head wind. The trailer loaded was 5400 lbs. I locked out 6th gear and it towed in 5th even through the hills. It was awesome. There were a lot of slow/passing lanes on the hills for slower traffic that I thought I may need to use but never needed to with all the reserve power. It never got above 2500 rpm's even on the longest steepest grades. Just set the cruise at 66 and it chugged along at 1800 rpm's. Many folks were staring in disbelief as I blew by them up hill. I have an EcoBoost 2WD with 3.15 gears by the way. If it was set up with gears for towing I can't imagine what this thing could do. <!-- / message -->

Great information. Thanks

Glad to hear this. Mine is coming with the 3.31 gears. Was a little worried about towing or if I wanted a little bigger tire. Originally wanted 3.55 but.....
Although the 0-60 or racing off the light may suffer;)

The 3.31's in my truck are all the gear that most people need if buying an ecoboost.

Remember, the 1996 and older F-150's with the 300 I-6's had 3.08's and still got the job done. The EB with the 3.31's is like a rocket. :)

I have the 3.73's that came with the max tow pkg and this thing tows remarkably well!! I have absolutely no complaints with this truck.