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Which Rear End for Dodge Dually?


brandman
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Long time reader, first time poster - so take it easy on the new old guy. 😊  We just bought our 5th wheel (2012 Bighorn) and am now looking for my truck.  It may be overkill, but I have decided to buy a 3500 dually (GVW of 5th wheel is 14,000).  I have never owned a diesel truck and am  looking for recommendations as to which rear end to get.  I was thinking 3.73, but found a good deal on a new one with a 4.10.  How bad will this hurt me on mileage when just driving the truck around town?  How about when towing?  I know there will be differing opinions, but that's OK.  We're hitting the road in mid June and I am just trying to get my ducks all in a row.  Thanks in advance for your help.

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In 100,000 miles 1 mpg comes to about 1000 gallons difference if your getting 10 to 12 mpg so about $3000. That's probably more than the difference you will see between the two referenced ratios. A lot will depend on how you drive. Slow down 1 mile per hour and you probably won't see any difference.  You will see a difference climbing hills and on long grades. Tires seem to have gotten taller over the last few years and as such you need lower gears to compensate. My 3500 has 4:10 and I have seen times I wish it had 5:10. Using my 8k trailer I average 14 (8000 mile trip) pulling my 14k trailer I get 10mpg. My truck is a 03 so it has a lot less power than the new ones. 14 is about the best I ever get even empty.

Edited by Lance A Lott
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Never had a camper the weight you have. Mine was 18k and 21k. My dually did get 12-14 normal driving. Long trips I have not idea as only towed long mileage. Now I never got over 7 with either camper and the Teton was 5-6. Both were Chevys and 3.73 gearing.  HDT actually get 7-8 which I have now.

Edited by GlennWest
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My Ram 3500 DRW has 3:73, pull an RV around 13k.  Depending on terrain, I get around 12-13mpg towing (mostly flatland), see a lot of unloaded 18-20.  Tows like a dream and still handles great without camper.  It's a good ratio to obtain the best of both worlds, driving loaded or unloaded.  Ppl complain about the transmission more.  The 69XXX model mine has works just fine but I would not chip it, that's where the problem starts.  There's a H.O. model with a stonger tranny and I think (don't quote me) 4:10 rear but unless you plan to haul real heavy, its wasted $$, IMHO.  Saying that about mine, I have not hauled in mountainous regions, might change my mind after this coming summer in the rockies.

Edited by NDBirdman
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With our 2003 Ram dually Cummins, 242,000 on the clock, we have pulled our 38' fiver with no problem. Now I do have a six speed NV 5600 standard tranny. Never have had a problem towing including Alaska. You should ask your self approximately how much towing versus running empty you might do. We tow quite frequently being full-timers since 2003 but since this truck is our daily driver also, we run empty much more.

I might ad, just thought about it, this is still the 5.9 diesel.

Edited by bobsallyh
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  • 3 weeks later...

We have 3:73's in our '15 RAM, gets around 18 mpg around town and about 9 mpg on the highway towing our Suites.  We weigh in at 27k to 28k depending on the amount of "stuff" we have with us.  The '15 has the HO Cummins and Aisin, it does a fantastic job towing up as well as down grades!   LOVE that EB!

 

Our '06 RAM had 3:73's in it and when we still had the Montana which was significantly less than the Suites, it pulled great!  The newer pick ups are awesome and rated for a whole lot more than the older models.

 

IMHO you'll do great with either choice, 3:73's or 4:10's, 4:10's do give you more towing capacity.

 

Dan

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I had the 3:73 gears on the old 1992 Ram1 ton diesel dually and despite it being gutless compared to my other Ram diesels, all with 3:73 gears - which were my 2002 Ram 2500 long bed, 2006 short bed Ram quiet diesel 2500, and my current 2004.5 with the 2005 quiet diesel Cummins 5.9. We traveled the Rockies over and over and did have to add an exhaust brake. Mileage was not as good as my later models. But I'd go 3:73 not just for the mileage, but for the lower RPMs at cruising speed. I had 12k even without filling my64 gallon Transfer Flow diesel tank.

Ram/Cummins power and performance was quite different from 1992 t5o my newer Rams.

This is one of those six of one, half dozen of the other decisions..

Edited by RV_
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I can't tell you the difference in MPG other than I came to the conclusion, based on what other's told me, that between the 3.73 and 4.10 it will average out if used as a daily driver as well.  One is better for running around town unloaded and one is better when towing.

I just bought our 2018 Ram dually with 3.73, and the high output engine came with the Aisin transmission. Friends have the same truck with a 4.10 and 3.73. I would have been fine with either 3.73 or 4.10 but we are using it for a daily driver as well. We will be towing a trailer with a GVWR of 16,000.

Or course you have to check the towing charts to make sure you are okay with whatever engine, transmission, gear setup you go with.  I would have definitely gotten the 4.10 gears if I had not purchased the Aisin transmission for a 16,000 trailer based off the towing charts. Also leaves room for a heavier trailer upgrade and add a margin of safety.

 

 

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  • 1 month later...

Thanks for your input everyone.  Tomorrow morning I pick up my new 2018 RAM with Aisin transmission and 4:10 rear end.  Pretty excited, but somewhat concerned with how high the bed rails and tailgate set from the ground.  Anybody have problems with this?

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Did you get the air ride?

I added 2 inch risers to my DRV and some even added 3.  Because I did this, I tow level and have good bed rail clearence.  Towing nose high puts more load on the rear wheels.

shocked the RV manufactures have not caught on that the truck manufactures are making taller beds.  Having the air right will give you a little leeway as you can lower the rear suspension.  You still might be nose high but it will be a little better.

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Mine has decent clearance but if not on a level road, or if backing and not level site, I get a little nervous as I think it's a little close.  My pin box put a slight bend in the bed cover rails one time, I had to be within a 1/2 inch of hitting the bed side.  I raised the Anderson hitch's ball up a notch (gave me lots of clearance) but that made the RV nose too high.  I lowered the ball back down and just use a lot of caution when I back/turn very tight.  I plan on replacing the camper in a year or so, so I'm not going to raise the camper, I just use a second set of eyes for now.

Edited by NDBirdman
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