3500 6.4 3.73 or 4.10

[Shield134]

Hey guys, new to the forum and wanted to get your opinions on a 1 ton 6.4 with 3.73’s or 4.10’s. I currently have a 2015 ram 2500 with a Cummings. I am leaning towards downsizing to a 6.4 cause I don’t tow heavy nearly as much as I did in the past. I do tow a 11.5k fifth wheel about once or twice a year. I was towing it all the time but since my wife and I put it in a seasonal site, my heavy towing is minimal, again a few times a year. So my question is for anyone who has experience with towing that weight with a 6.4, should I go with the 3.73’s that max out at 12.6k or go for broke with the 4.10’s that top out at 15.6k. The only other trailering that I do is a 3500 lb boat so that’s no issue. The 6.4 will also be my daily driver. What do you fellas think? Deal with the 3.73’s a couple times a year towing the 5ver but reaping the benefits of better fuel mileage as a daily driver or get the 4.10’s?

 

[G. Mcpherson]

I would go with the 4.10. Fuel economy is really not much if any difference at all from what I have read from many on here. You will have better towing capability for sure.

 

[BlkZrx]

4.10's for sure. The 3.73 is geared for the diesel. Mileage difference wil be negligible.

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[theviking]

It's the same trans ratio in both the 66 and 68RFE. In other words, it's far from optimal with the gas engine. Under full throttle my truck doesn't shift into 3rd until after 70mph and that's with the 4.10 gears. So..get the 4.10's if you are going to do any heavy towing at all. And good luck finding a dealer that has one in stock.

 

[LDBagger17]

absolutely 4.10's

 

[mohemipar]

I say 4.10s also. You might regret not getting them but you definitely wont regret getting them. I wish Ram still offered a 4.56. Would be great on this truck.

 

[Rampant]

You'll be fine either way. Most people who have an opinion on this have zero experience with it. I have a '16 2500 Laramie CC/6.4 all stock except CAI and 35x12.5x20 tires. It has 3.73 gearing. My truck has 32k miles on it. Over half of that has had my race trailer hitched up with different vehicles/cargo in it weighing anywhere from 7k to 13k. No issues. It does a great job, no matter what the situation.

Cummins have 3.42 gears, not 3.73, and twice the torque. It's not a Cummins and I don't expect it to tow like one.

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[Shield134]

Thanks for all your help guys! I really appreciate the responses.

 

[HvyDuty]

The spread from 3.73 to 4.10 is small. Though with the 4.10 you gain 3000lbs of legal towing capacity and GCWR. I do agree that 4.56 should be an option with the 6.4 and 66RFE and more than a few here have swapped to 4.56 or higher and seem to love it.

 

[NewBlackDak]

4.10s hands down. Mine has 4.10s, and I’ve had a 3.73 loaner twice. You can tell the difference, and it’s worth it.


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[Danno]

4:10 or move to the 4500 with the Aisin transmission. MPG between 3:73 and 4:10 is minimal if not better in a 4:10. The cost of a 4500 can be leas depending on trim.

 

[6.7CumminsDrvr]

Well, my deleted ‘10 had 3:73’s and I wished that truck had 4:10’s.........

And the tranny ratios were developed for that engine, Just say’n

 

[Phil21502]

I have 4.88's in mine with 35's. Love it! Although if I could go back I'm pretty sure I'd do 5.13's. I get 14 mpg avg. with mds shut off.

 

[smurfs_of_war]

4.10s would be the best choice but 3.73s will do just fine if that's all you can find. I don't tow a fiver of that weight but our dump trailer with skid steer and parts is definitely pushing that if not over that and it motivates it just fine with the 3.73s. The gap between the two is pretty small, so mileage really isn't worth worrying about. Damn near identical I'd bet.

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[reek]

4.10's for sure. The 3.73 is geared for the diesel. Mileage difference wil be negligible.

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Ironically, the Cummins is only available with the 3.42. Not sure where FCAs head is.

OP, go 4.10 while you can. never know when they'll take that option from us.

 

[SouthTexan]

A 6.4L with 35's and 4.88 gears gets 14 mpg average......

My Cummins with stock tires and 3.42 gears would only get 14.5 mpg average(hand calculated) before deleting it.

 

[reek]

You'll be fine either way. Most people who have an opinion on this have zero experience with it. I have a '16 2500 Laramie CC/6.4 all stock except CAI and 35x12.5x20 tires. It has 3.73 gearing. My truck has 32k miles on it. Over half of that has had my race trailer hitched up with different vehicles/cargo in it weighing anywhere from 7k to 13k. No issues. It does a great job, no matter what the situation.

Cummins have 3.42 gears, not 3.73, and twice the torque. It's not a Cummins and I don't expect it to tow like one.

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Goes both ways, if you've never tried the 4.10, 3.73 feels just fine. I've towed with both, the 3.73 (father in laws) and my 4.10. Yes they both get the job done well. the 4.10 just feels a lot better doing it. but if you've never tried both, you probably wouldn't really miss the 4.10.

 

[BlkZrx]

Ironically, the Cummins is only available with the 3.42. Not sure where FCAs head is.

OP, go 4.10 while you can. never know when they'll take that option from us.

I guess I should have said the transmission is geared more for the diesel..

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[SwollenMonkey16]

If you have the option between a 3.73 or 4.10 that they do happen to have on the lot then I'd go 4.10s but like we all know its going to be tough finding a 4.10 on the lot. And also like previously stated the 3.73 will get pretty much any job done so the only comparison you'll have is between your new truck and your old diesel which no gasser can compare

 

[SouthTexan]

Ironically, the Cummins is only available with the 3.42. Not sure where FCAs head is.

I actually like the 3.42 ratio with the gears of the 68RFE. Since both 5th and 6th gears are overdrive gears, I use 6th as an overdrive unloaded or towing light and 5th as overdrive when towing heavy. Pulls my 14k(loaded) 5th wheel 70 mph at 1,900 rpm in 5th gear and just stays there for the most part unless the road gets really really steep. Pulling with a 3.42 rear end in 5th actually has greater torque multiplication than a 3.73 pulling in 6th, and the rpm's pulling a 3.73 in 5th at the speeds I tow (usually 70 mph) would be screaming for a diesel.