Help me out with finding the right truck for me. I want to get back into a diesel. I had a 7.3 for many years and sold it some time ago. Wanting to get a 6.7L DRW but finding the one with a 4:10 seems difficult. Not sure why. Correct or educate me on this if you would. Am I not correct that the 4:10 rear end option would provide me with better fuel economy and the best towing capacity in a F350 DRW? I have looked on Marketplace and Auto Trader for a few weeks now and everything I find has the 3:73's in them. I need to pull at least 18k lbs and I know either one of those should do the job, just want the best option out there even if it is a few more bucks. Thoughts..? Thanks James

 

If you are looking at 2017 and up duallies wih a diesel engine, you only options are 3.55 and 4.10. They quit putting 3.73's with the diesel in 2017. 4.10's will give you the worst milage and 3.55 the best.

 

With the 6 speed transmissions the 6.7L combo is hard to beat. I can and have towed as heavy as you are wanting to - with 3.55's - no problem. I have a taller final drive than a DRW also, 20" wheels.

The 3.73's are a good middle ground. However, I am pretty sure that gear ratio went away as an option in DRW's around the 2016 or 2017 model years. As to why I am not sure. The 4.10's will give you better torque to the ground, and will give you a higher payload, all other factors being equal, but you are going to loose fuel economy with the higher RPM's. If you have a trailer behind you that heavy all the time then maybe that is something to consider, but otherwise I don't think you'll find it necessary.

I wouldn't shy away from the 3.73's one bit if it were me. If you have yet to pull with a 6.7 I think you will be surprised with what you are stepping in to from a 7.3. I drove a mid-90's era 7.3 dually picking up steel earlier this year. I didn't scale, but the steel was less than 3000lbs on a tandem axle equipment trailer. Fuel mileage was in the single digits and accelerating was a dog. In comparison, we did some property maintenance with an old allice chalmers tractor and brush hog mid-summer and I pulled it with my 6.7. Weight was well over 10,000lbs, maybe 12-14k, and I had no trouble pulling it at all.

Best of luck with what ever you decide.

 

I have a 2013 DRW with 3.73, It does great.

Check this video of my truck towing over 15K from a stop at one of our truck meets

 

Pulling my 16K fifth wheel over generally flat land (driving gently like the grandpa that I am) all that I've gotten is 8/9 mpg.
I've not yet had an empty load so can't say what it'd get there.

My TV can be seen below, now clocking in at around 2100 miles.

 

In my '15 F250 I had 3:73's and towed my Coachman for several thousand miles, mostly on Florida flatlands. Got my '18 F350 with 4:10s mainly for a planned trip up to the Tennessee hills and my, hopefully, future endeavors out west. No noticeable difference in the feel but I can see on the tach the difference in eng revs. I know the F350 doesn't strain as much. Less than 1 mpg difference when towing between the two and 2-3 mpg difference with no load but if I was that concerned about economy I wouldn't be driving a PSD.

 

FWIW, the 2019 Ford F350 DRW towing chart shows with the 4x4 crew cab 6.7 with 3:55 gears will pull 27,300 lbs. Same truck with 4:10's will pull 31,300, both on a 5th wheel pull.

 

I have the 4.10 and wouldn't give it up for love nor money.
When towing, fuel consumption is very speed and wind dependent. Pulled a heavy 5er last week - heading into the wind I was getting 8 mpg @ 60 mph, when the wind died it jumped to 11 mpg @ 60 mph. Increasing speed to 65 mph would have knocked me back to 9 or 10 mpg in that situation.
Running empty @ 65 mph nets 16 mpg on average while 60 mph will boost it to 17.5 mph. I have driven @ 55mph and earned a whopping 23 mpg over 300 miles.

 

The only advantage of a 3.55 or 3.73 over the 4.10 on a dually is mpg when empty. The higher the speed empty, the better the mpg difference. At 65 a 3.73 gets me 1.5 mpg better than the 4.10. This is average over 30k miles, not just a tank. If you travel empty a lot at 80 mph, you might save a few bucks.

towing is a whole different story. My 5er is 16,500 loaded and 13.6" tall. Pulling from a dead stop on level ground the 4.10 was an advantage, an a slight incline, a huge one. Mpg loaded like this there is zero difference between the two, unless I have a tail wind, then the 3.73 is a bit better. Gear selection on tge 4.10 is much better on step hills and in the mountains - a lot less shifting, and more often no shifting needed. Yes, rpms are up a bit, but you stay in the torque curve, and interior noise is minimal.

With that load, I would not get the 3.55.
You will likely need air bags. Toss the oem shocks.

good luck,

johnD