I'm trying to figure out all the details for a 350 to serve as a new tow vehicle. This will be wayyy too much truck for my current needs but I'd like to be able to tow a shorter, lighter 5th wheel in the future. The largest trailers I've been looking at for reference are in the 10-11k GVWR range. All of the weight numbers work out but I cannot figure out if the 3.31 axle would be enough with the 6.7L standard diesel. The current configuration I've saved is using the 3.31, but how much would this struggle on hills and steeper inclines to accelerate and maintain travel speeds? For reference, we're on pace for around 60-70 days this year in the camper and will only grow in future years. Want to start visiting national/state parks and general travel in North America. Would I be disappointed with 3.31 performance with heavier trailers or should I swap around options so we can upgrade to the 3.55?

ETA The FX4 package is what is currently "restricting" me to 3.31 but I don't see much that can't be added or enabled after delivery.
- Hill Descent Control - can this be enabled with FORSCAN? At first I thought this was the engine brake but this looks different. I doubt it would be needed ever but still curious if it could be enabled.
- Shock upgrades - can be upgraded later if necessary
- Skid plates - can be added later if necessary
- FX4 decal - outraged I'd miss out

 

IMO the FX4 package is a waste of money for what you get.

Factory shocks are junk no matter what package you have- you'll have to upgrade to Fox, Bilstein, or another premium shock if you want something good

Hill Descent Control- Only time I've ever used this is in a parking garage, the other 99.9% of the time I've never used it

Skid plates are a must for me and are a stand alone option. If not buy some aftermaket plates that are better quality

FX4 Decal- buy one if you want the look.

If it was me I'd skip the FX4 and get the 3.55 gears

 

The standard 6.7 has a claimed 1000 lb/ft of torque. They do not offer a gear ratio that motor can't pull. The 3.31 is probably rated to tow over double what you heavier trailer will weigh. With the ten speed trans there is almost no performance difference between 3.31 and 3.55. You are concerning yourself over something that is absolutely not a problem.

 

I am pretty sure the ONLY way to get skid plates on a '23 is the FX4, it is no longer a stand alone option. It is also by far the cheapest way to get decent skid plates. Aftermarket or used will cost way more than the FX4 option.

 

Thanks for the insight. This is where I'm leaning and why I asked

Thanks for the insight. This is where I'm at right now but still wanted to ask about it. This vehicle will still be my daily driver so I don't want to overlook the fuel economy advantages of a smaller gear ratio.

 

Based on the tow guide for a ‘23 SRW both the 3.31 and 3.55 are more than capable for your listed weights. I don’t see a need one way or the other, and unless someone has both a 3.31 and a 3.55 to do a comparison you may just need to order based on the features that come with the truck. What I mean by this is, I would order based on if the need for the items you listed, skid plate, shocks, hill descent and so on. I don’t think a gear as close in ratio as the 3.31 and 3.55 would be my deciding factor. Not that I could get a 3.31 in my case (DRW) but I prefer the 3.55.

 

Good point. The reason I'm going with a 350 over 250 is total payload concerns since pin weight is heavier percentage of trailer weight. The overall trailer weight is still very small for what the 350 could pull so the axle ratio wouldn't be as critical.

 

That's what it seems like. The online configurator prompts me to add the FX4 package if it's not selected and I try to add on skid-plates. Looking at the order guide, it appears they are only available with the XL offroad, FX4, and Tremor packages

 

With the ratios in the 10 speed trans, the 3.31's will pull ANYTHING you hook the truck to over the tallest mountains without breaking a sweat.
And, there is so little difference in ratio between 3.31 and 3.55 you would never feel the difference.
So, if some package you want, restricts you to the 3.31's, don't worry about it at all, get the package and move on.

 

I am towing over 15,000 pounds with 3.31s. It handles it just fine. The 10 speed transmission makes the difference. My 2016 6.7 6 speed had 3.55s. I didn’t notice any drop off with the 3.31s on the 2022. When you look at the actual final drive ratio between the two, it is the same in 1st gear and 6th gear in the 6 speed 3.55 is the same as 9th in the 10 speed 3.31.

 

The only way the 3.31 ratio might bight ya is if you’re planning to “upgrade” to 37” or larger tires. That’s not a modification I’d recommend for a tow vehicle anyway. YMMV

 

What they said; it doesn't matter for the weights you are talking about. Mileage won't be any different either. That said, I'd choose the 3.55's especially if you plan on bigger tires which, it seems, 90% do (not me). I don't think the FX4 is really worth ordering and IIRC, skidplates were still a separate option on the Canadian configurator when we ordered our 2023 but we didn't order them. I'd pick the 3.55's over the FX4 but you'll be just fine either way. I tow my 10,000 lb load up any hill at the speed limit.

 

10-11k trailers are F150 territory. Don't worry about the gears in a 6.7L F350. LoL

 

if what you’re saying is true then this is a good reminder to not believe everything you read on here. The post was made sounding like he had the utmost certainty yet every last bit of it could be incorrect.

 

5th wheels are not, which is what I'd like the capability to do. They weigh too much.