For the 2017 model I had to add the camper package to get the 3.55 gear ratio. That was fine with me as I wanted a sway bar anyhow.

 

 

That is interesting. My build is a platinum and it doesn't require any sort of heavy front suspension. Click on 3.55 locking and it has no popup.
(nothing really to take a picture of as there is no popup to show this)

Why would Ford do that?

 

Maybe because the Platinum package has the 20" wheels. My Lariat Ultimate package had the 18" wheels. I'm speculating here.

 

Winner winner for the smartest response. Yep, both are fine. The reality is that I'd bet 90% of the posters on this thread or forum for that matter would be unable to tell the difference in a side by side bakeoff towing. When people talk about downshifting climbing passes, I can make any truck do that by pressing hard on the pedal on the right. It's all anecdotal as we all drive differently.

FWIW, at 8k plus gear and family and a full tank of fuel, I did not come down out of 6th on Snoqualmie pass and maintained speed with a 3.31. But, I will admit, there must be a difference to the truck as I did a 100 mile highway trip the other day and the trip OD had me averaging 26 mpg on cruise control at 60mph. You really can't go wrong here.

 

I really don't think there is much of a difference either. If at all it's a mathematical equation only to debate. If it comes down to an issue... Just down shift the transmission. No Biggie. Even a low gear ratio will have to downshift at times for cause.

 

Since Ford paired the 3.55 with the snow plow prep package I can't help but wonder if the shorter gear was intended as much for plowing as towing.

The 6.7 doesn't suffer from the same characteristics as some gassers but on my old 5.0 Clubwagon (van) towing at 65~70 mph with the 3.31 gear had the motor off the bottom of the torque curve and made it difficult to cruise on anything other than perfectly flat ground. Switching to the 3.55 gear (the optional tow package gear) made a significant difference. The motor was now up on the torque plateau and would pull comfortably on most terrain without downshifting. So in some situations a couple hundred rpm can make a difference.

 

The Build and Price site has a flaw. It forces the HD suspension when selecting the 3.55 gear ratio, however if you order your truck with the 20 inch wheels then you can get the 3.55 without the HD suspension. The 18 inch wheels force you into the camper package to get the 3.55.

Clear as mud?

Haha.

I have a 13k 5th wheel that I tow with the 3.55 rear end and it tows it amazingly well. OP if you are ever considering up sizing your tires then you definitely need the 3.55 and even with stock tires if I were towing 50% of the time I would most definitely opt for the 3.55.

 

My buddy and I have almost identical trucks, both 2017 Black F250 PSDs, we even have the same factory wheels with 295/65/20 Ridge Grapplers. I have the "inferior" 3.31s and he has 3.55s. We recently pulled our TTs over to Gulf Shores Alabama from Houston, following each other, his TT weighs about 8k and mine is closer to 10k. Both trucks did fine, we ran 75-80 all day long on I-10 and I averaged about .3 mpg better than he did according to on board displays. I averaged 10.4 and he averaged 10.1, both reset at the same time and even filled up at the same fueling stations. My theory is that these engines are more than capable for those loads so my slight gearing advantage attributed to my slightly better MPG. The only reason I mention they are both black is because everyone knows the black ones pull better than the other colors, your results may vary.

 

 

 

Exactly why I noted the difference in torque curves. If you were towing at a speed that had you below 1500 rpm you would be significantly below peak torque. Which probably wouldn't matter that much. The van only made about 240 lbs/ft max. So it mattered.

Unless you were towing something that had a tremendous amount of aero drag, that was heavy and you were in the mountains frequently, I doubt that much difference in gear would matter much.

 

Same here except I ordered my truck with the 3.31 gears. F-350, diesel, CC, SB. I tow a 16,000 lb. fifth wheel and it is just fine. When I am on a steep grade I sometimes wish I had a lower final drive ratio, but all other times I am happy with the performance and fuel economy with the 3.31.