cajun bill

Searched the threads, but didn't find one which specifically addressed this topic. The situation is that I'm very close to pulling the trigger on a 2016 F150, 3.5 EB, Lariat with options galore. My question pertains to whether I should go with the 3.31 or 3.55 rear end. My particular situation is that I will be pulling a 4,000 lb boat about 20 times a year and a, as yet unpurchased, travel trailer that will be within the specs for the towing capacity of whatever F150 I buy. I suspect it'll be no more than 8,000 lbs, but not sure and I will very infrequently have to tow it as it will be a hunting trailer used on a campsite only during hunting season at a spot about 150 miles away.

I was thinking that if I get the 3.31, I might be able to expect better overall fuel mileage since most of the, I will use it as an all around vehicle for both highway and urban driving and not towing anything. All thoughts would be appreciated. Let the games begin

me1234

I would go 3.55, honestly 3.73 if possible. You'll get more torque off the line but the engine will be slightly faster at highway speeds. The way I see it, why buy a top option truck if you're going to limit the engine's usable power by buying high gears?

PawPaw

I've got the 3.31's in my truck but wish I had the 3.55's especially with the 33 " tires I have. For towing up to 5K pounds the 3.31 is OK but any heavier I'd opt for the 3.55's. You'll get good fuel mileage with both gear ratio's.

SteveLord

Agreed 100%. Except the 3.5 Eco 3.73 gear option is a little more limited now. You can only get the 6.5' screw or the 8' bed scab with them.

marshallr

Any difference in fuel mileage is on paper. Real world you won't see any difference. While the 3.31's combined with the 3.5 EB will probably have all the power you'll ever need. It never hurts to have the the lower gearing option. In this case there is no downside to the 3.55's

schmart

I've got a 2012 SCREW EB with 3.31 gears and have pulled a trailer and a full size Chevy PU (Forever On Repair Duty you know...) and had absolutely no issues with all the power that I needed. Assuming the tongue weight distribution is correct, you won't even know the boat is there.

That said, I haven't seen any real world improvements on fuel mileage, and as most is in town, seems I get slightly worse than others with 3.55 gears claim. If I had to do it over again, I'd go w/ the 3.55 gearing. Either way, I suspect you will be happy.

WXman

If you're superhuman unlike the rest of us and you can detect a 150 RPM difference on the tachometer on the highway, then I'd go 3.55. The average person could never tell the difference between two identical trucks with different gear ratios unless you told them.

Having said that, there is a slight bump in torque/overall power in the lower transmission gears if you have the 3.55s vs. the 3.31s so if you ever launch a boat I guess you'd notice it a little then. Or if you go offroad at all.

mike243

I have 3.55 in both of my 150's,the 02 has a 4.2 in it and have owned since new,take off with the 02 is a little under powered until the rpms come up some then no problem pulling at any speed,the 5.0 over comes the power issue on take off.I think the 3.55 is a good compromise. I had a 1968 f100 with 373 and a 302 3 on the tree that was bad on gas but stout on pulling. No bad choices just better choices to choose from as only you know how much you tow yearly

JCR 56

3:55. 3:73 if available.

Platinum T.C.

I've had both 3:55's & 3:73's. Never ever wanted the 3:31 for colorado Mountain roads.

I prefer the 3:73's.
My last two f150's have the 3:55. 2014 4x4 3.5 Lariat & my New 2015 FX4 3.5 Platinum.
There is very little difference in Gas mileage between the two.
I assume you are from the South?
The better choice would be the 3:55. The better of both worlds.
Please remember you are buying a Truck, not a Honda Fit. Gas mileage will vary.