3.73 or 4.30 gears for F350 carrying Scout Kenai?

[Jamie131]

Hello! I am in the process of purchasing a 2022 F350 with a 7.3L gas engine for my Scout Kenai (currently on order). This is my first truck and first truck camper, and I am debating between the 3.73 and 4.30 gear options. I am in the northeast and will be driving on plenty of hilly terrain. I went with the Kenai because I'll be using it year round, so I'll also be driving in plenty of muddy, slushy, snowy conditions. My young son will be in the car with me and I'll be driving slowly and carefully. I've been reading through the Super Duty Ford forums and folks are very split on the 3.73 vs 4.30 issue. Seems like the 4.3s are great for hills, but the 3.73s are better for fuel economy. I'd love to hear any thoughts or advice from those with truck camper experience. Oh, and the camper will be living more or less permanently on the truck. I'll be using another car as a daily driver. Thanks so much!

Jamie

 

[Ninelitetrip]

Congrats on the new setup.

Will you be going from the stock tires to a larger size tire. Say from a 33" to a 37" or staying stock?

Will you be towing? Often or just occasional? Heavy, say 15,000 lbs. or a utility trailer to pick up some lumber?

4x4, rear locking differential option?

If you are staying stock tire, or maybe going up one size only, and not towing, 3.73 if you want slightly better fuel mileage. Nice thing is you get that 10 speed transmission.

What trim level you going with?

 

[IdaSHO]

Since you are buying new and have the option. 4.30’s without question.

With the 10-speed the truck will only be happier. And with it being a triple overdrive trans, your MPG shouldnt be affected. It may even improve it.

 

[Jamie131]

Thanks for your replies! To answer those questions- I will almost never be towing. Just the camper in the bed. And yes, 4x4 with rear locking diffs. I will stay with the stock tire or maybe go up a size. Not planning on putting huge tires on. And it's a base XL trim. I actually prefer the vinyl seats because with a toddler wipeable is best!

 

[billiebob]

3.73 has the advantage of lower rpms on the Interstate. If you'll be doing lots of Interstate.... pick the 3.73. The advantage of 4.30s is better control at low speeds off road. Off road neither will give better fuel economy. On the Interstate if you decide on monster tires you'll need the 4.30s or deeper just cruise. But if economy is a priority stick with the stock tire size. Gearing has little effect of fuel economy once you go the monster tire route. Low gears with big tires just guarantees you can accelerate to pass. But it is real easy to drop below 10mpg once you start lifting and adding rubber.

Lower speeds, off highway lots, bad driving conditions, a camper always loaded.... go for the 4.30s. In those conditions the 3.73s will not improve mileage.

 

[grindmonkey]

I did this dance a little bit ago.
I have a Hallmark Cuchara. So, probably about the same weight but different height profiles. I went with the F350 7.3l CCLB with 3.73.

The 3.73 will generally get better MPG. But if you think you may need a little more payload the 4.30 will most times get a few hundred lbs more. (There was also an issue, recall/fix, for a little bit with the 4.30 rear ends when I was ordering, FYI)

I was getting 13-18 (city/hwy) before the camper for the first 1000 miles. With the camper (mounted full time) I will get 9.5-13. I have not been left wanting for a lower gear yet with about 5000 miles of mostly winter driving through the Rockies in Colorado.

Now, with that said, if I end up talking my wife into letting me get a couple of snowmobiles and a trailer i may wish i had the 4.30..... but i am probably closer to winning the lottery than getting snowmobiles.

 

[tacollie]

You're getting a camper on a F350 so mpgs will never be great. The 3.73s will only help an unladen truck. I would get the 4.30s since your truck will always be loaded. If you want better mileage stick to under 65mph.

 

[Jamie131]

Thank you to everyone for your feedback! After some deliberating I decided to go with the 4.30s. So that means I've now got a F350 7.3L with 10-speed transmission officially on order! With the Kenai coming in at around 2,000lbs wet, I'm relieved to have enough truck to not have payload be a worry. As for the gas mileage- did I mention I used to drive a Honda fit? So it's going to take some getting used to. But I'm excited to get this truck on the road and kick start a life time of outdoor adventures with my son. Thanks all!

 

[IdaSHO]

Congrats. Should be a great setup.

 

[mk216v]

I concur on the 4.30's, and since I'm in the middle of installation of 4.88's (on a truck that came with 3.73's) due to going with 37" tires, let me just say that it's SOOO much less $ to go with factory 4.30 gears vs upgrade later.
Enjoy your package, should be awesome for you and your son!

 

[deserteagle56]

You made the correct decision. With these new transmissions, the 4.30 gears will allow using those overdrive gears more and improve driveability overall.

Some years ago I regeared my E350 from 3.73 to 4.56 because every time I came to a hill the transmission would shift down out of overdrive and engine rpms would soar. Regearing solved that. My fuel mileage before regearing was 12 mpg. After regearing - it is still 12 mpg.

 

[montypower]

4.30 Gears for sure. Better towing, ready for larger tires, better in town MPG, better resale and cheapest factory option ever! Aftermarket regear will easily cost $2-3k.

I doubt there is any MPG hit. But if there was... it would be ONLY when traveling empty at high speed. Really isn't a great idea to drive high speeds with a HD truck. 65mph is plenty fast and better mpg. Wind resistance is rather significant.

 

[jadmt]

I would wager that the difference in real world mpg for normal driving is going to be nil..Ford got it correct by giving 4.30 option. I wish RAM did the same. I have 4.10's and 100% go 4.30's.

 

[mk216v]

Better in town MPG, due to being in a sweeter spot of the RPM's?
4.30's from the factory certainly are a huge bargain.

 

[jadmt]

one other thought. I have been reading various truck and jeep forums since forums became a thing and in all that time I am trying to recall how many posts I have read where people have wished they went lower numerically then what they had and I have read many many posts where people wished they had gone numerically higher. I have never read a post where someone has paid to re-gear a higher to lower numerically gears but I can not count the other way around times. just something to think about.