Choice of rear axle on 2016 F350

[SunBirds]

Hi everyone. We're ordering a new F350 (4x4 CC LB Diesel) and are trying to decide between the 3.73 and 4.30 rear axles. Presumably the 3.73 will have significantly better MPG, both empty and towing, but I can't find any information on how much the MPG will decrease with the 4.3. Any information -- even 'guesstimates' -- will be appreciated.
FYI, the numbers: tow capacity 3.73 (23.5K), 4.3 (26.5K). The 4.3 also comes with the better handling 'wide-track' front axle (per description of 'TRAILER TOW PACKAGE – HIGH CAPACITY (535)' in 2016 ordering guide) and increases GCW from 31.9K to 35K. We will be towing a fifth wheel with about 16.5K GVWR for the foreseeable future, but ... who knows :). Thanks in advance.

[tinner12002]

I would also look at the tow rating for the truck...I know on my Ram in my sig they list the tow rating to be around 6000lbs less with the 3.73 vs the 4.10 gearing that I have. They had one on the lot identical to mine other than it had 3.73 gears, I ended up ordering mine to get the 4.10s. Much easier on the truck and drivetrain with the lower gears. I checked the rpm of both trucks driving at 60mph and there was only about 150 rpm diff as close as I could tell so I can't believe there would be hardly any difference any mileage. At about 58mph my comp shows I'm getting around 21 mpg with 4.10s.

[transferred]

Wide track is awesome. Axle ratio unimportant with today's engines in pickups. Congrats you'll love it.

[SunBirds]

Well, after much discussion (and coin flipping, sessions on a Ouija board, etc.), we decided that the extra maneuverability of the wide-track front axle outweighed the MPG loss of the 4.3 rear axle. Thanks everyone for your help and advice. Can't wait for the truck to arrive (I want it NOW!!!):B

[broark01]

Had a 2012 F350 6.7 SRW with 3.55 and now have a 2015 F350 6.7 DRW with max tow package (wide track and 4.30). When towing I have seen no significant difference in MPG.

When not towing, there is at least a 2 MPG difference on the highway. That said, the turbo is different between the 2 so it might be part of the equation.

The 2015 6.7 4.30 has neck snapping acceleration that makes me smile whenever I put my foot into it.

[SunBirds]

Thank you all for your advice and opinions. Got some more thinking to do; I'll let you know what we decide.

[transamz9]

I'm going a little different on my preference of gears. I currently have 3.42 and with the torque of today's diesels have zero issues getting took off. Matter of fact I have had my traction control kick in a few times taking off on wet black top on slight inclines pulling my 20,000 rig. Running down the interstate I just lock it in 5th and roll on at around 1800 rpm which is close to 70 mph. When running on the two lane back roads I lock it in 4th. I have zero power issues with my high gears. If I had a choice in gears I would go with the 3.73 if I towed full time but my truck is a mixed use truck and when unloaded or towing the boat the high gear is great. My fuel mileage is great for an 8,000# truck and you can't here the engine running down the road because it is basically idling. JMO of course.

[rickeoni]

Get the wide track front end, the driveability with it more than makes up for lowe gearing.

[davidaf]

Can't answer what the difference in MPG would be as all I've owned is the 4.30 but I can tell you the minimal delta is more than made up for in the value the wide track provides. It is what sold me on the Ford over the other test drive vehicles.

[Oldme]

The lower gear 4.30:1 be better for towing any load.
This will be most noticeable on starting off and hills.

The 3.73:1 will give slightly better MPG when unloaded.

Just to compare my E450 based Class C is a 4.63:1.

Gear are your friend when towing.

[taken]

I tend to agree with everyone that 3.73's are plenty with the torque of the modern diesel. BUT... what most have ignored is the benefit of the wide track front axle that comes along with the 4.30's. It is night and day better than the standard front end for maneuvering. I would not buy a DRW without it.

PS: Are you sure you don't want to wait for the 2017 redesign? You're buying a very nice but outdated truck in opting for the 2016.

[TakingThe5th]

If you were to get the 4.30 and you later decide that you need to swap it out for the 3.73 - you would still have a truck with the wide track front end. Just saying.

[Dave_H_M]

I could not imagine going lower than the 3.73.

I ordered the 4.30 in my 2012 gssser and now wish I did not. i could run in 5th gear and be at the same point as the 4.30 in 6th.

With your bigger torque at lower rpm, I would not have to even contemplate lower than 3.73.

[BenK]

IMHO....Depends on the transmission gear ratios...


Always...the lower (higher numeric) will 'perform' better (AKA towing), but
suffer lower MPG (car attributes IMHO)...


Always...the higher (lower numeric) will have higher MPG and lower performance...


If me, I'd get the lowest (highest numeric) diff ratio as long as the tranny
has a good OD. Newer these days has double OD and why (again, IMHO) the lower
diff ratios (higher numeric) better for towing


Bottom line....decide which is more important...MPG or Towing performance

[Bedlam]

I think it will do fine with 3.73, but you will find the transmission shifts down to fifth more often on hills and in headwind. Since my truck is not driven unloaded often and not a daily driver, the higher ratio works for me. I live in an area that has 3000' climbs within 50 miles, so that is also a factor compared to someone that primarily travels the flats. I also like initial low gearing when starting on an incline - I never feel the transmission is struggling to get the load rolling or overworking the torque converter. Although I try to avoid city traffic, I am geographically bottlenecked and typically have to drive through congestion to get away from it. I never gave much thought to advantage of lower gearing through these areas, but I'm sure it helps too.

If all of your truck usage is towing and hauling, you will not be disappointed with the 4.30 ratio.