I have a 08 ram 4x4 hemi automati with 3.55 axle. On highway i average 20 MPG but as soon as i get my Travel trailer on, he fall's to 12 MPG no matter wind or not. Friends of mine as 3.92 and he average 15 MPG loaded. It's simply the mds that is kicking off. Same thing for me, 87 octane is better while loaded but 89 is much better unloaded on highway. But in your case, don't worry, hemi power under the hood means way enough power to haul.

 

Sorry for being late to the party on this tread but I just had a recent experence that might add some useful perspective. I have a '09 Crew Hemi with the 3.21 gears. I pull a 5,000lb travel trailer (fully loaded weight) with little problem except for downshifting on grades which puts the RPM in the 3K range.

I'm considering changing out for the 3.92 for one specific reason, REVERSE! We camp a lot in the mountains and need to back into sites that could be on an incline. This past weekend I almost burned out my trans backing up a slight to moderate incline. The trans temp was almost at the top end of the gauge and the truck wouldnt move unless I rev'ed the hell out of it. Had to do it because I was blocking traffic. So i'm hoping the lower rearend will make up for the higher gearing in reverse.

Hope this helps

 

One advantage to a 4x4 just put it in 4low, thats what I do backing my TT up into my back yard.

 

Well, the gear change-out is not going to happen soon. the dealer est. is $1,864 parts and labor.

 

That seems like a lot for just one differential.

 

Bearhog, if you are really set on change out, you can get the WHOLE rear end assembly, and put it in your self cheaper than that, have it installed in a few hours
http://www.wholesalemopar.com/parts_catalog.html
1337.05 for a complete POSI 4:10 rear end and that was just one place I checked

 

Thanks for the head's up! I checked the website and found exactly the part and price you referenced. I also found it very interesting that the other higher ratio axles were priced higher with the 3.92 being the highest at $2,184.

How do you like your CST lift btw?

Thanks again for your help.

 

One more late reply...

I have 3.21s in both trucks, and they tow our 20ft boat no issue, including a 250 mile trip to my parents-in-law. Tow/Haul doesn't seem to do much other than kill the MPGs really badly (single digits). I guess the boat & trailer is about 3-4K.

 

Bear......I really like my lift.......it makes the truck look a lot different than it did. Rides almost stock, great height

 

Where on the axle is this found. I crawled under mine and didnt see anything that I could understand...It look like a part number or something.