Rear end

[G Frank]

I have a 2002 1500 4.7L Quad cab with long bed. I just replaced my rear end with a used 3.55. It is starting to make some noise after about 7k. If this rear end is also bad, I'd like to to buy a new replacement but a higher ratio rear end to improve gas mileage, but not sure there is such an animal? I have been pulling a 4,000 lbs camper 6-7 times per year. I'm tired of getting 8-9 mpg. Thoughts, cautions?

 

[RamFP620]

Not sure if you're going to a higher ratio rear end will get you better gas mileage. Unfortunately towing = bad mpg.
I have a 5.7 with 3.92 gears and get about 10 mpg towing with 7300#

 

[dhay13]

I really don't see you getting any better MPG with a gear change. If anything go to a 3.92 since you may have to replace them anyway but the difference won't likely be noticeable. I towed my sons ~7000lb TT with my 2013 1500 3.55's and got about 6.5 MPG hand calculated from Pittsburgh to Buckhannon, WV (about 200 miles). I made it about 150 miles before ,y low fuel light came on and filled up right before I left home.
3.21'smay get you better mileage on the highway empty but towing or in town stop and go 3.92's will likely get better MPG, although not enough to notice. Guessing might save $3-5 per tank?

 

[Dodge trucker]

I rebuild my own. As long as gears aren't scored, bearing and seal replacements aren't too bad.
I did just do the junkyard thing on my 01 Durango 3 months ago when its front diff pinion bearings started to howl. Couldn't beat the price, got one with less than half the miles, was gettin ready to go camping. so far so good.

 

[RamInfo]

I have a 2002 1500 4.7L Quad cab with long bed. I just replaced my rear end with a used 3.55. It is starting to make some noise after about 7k. If this rear end is also bad, I'd like to to buy a new replacement but a higher ratio rear end to improve gas mileage, but not sure there is such an animal? I have been pulling a 4,000 lbs camper 6-7 times per year. I'm tired of getting 8-9 mpg. Thoughts, cautions?

I had an ‘01 Dakota with the 4.7 and 3.92 gears and periodically towed a Kubota backhoe with it, probably weighed close to what your camper weighs. Changing gear ratios probably won’t get you better mileage but switching to 3.92s will definitely make the tow easier and might actually get a bit better tow mileage than your 3.55s.

best,
DG

 

[mtofell]

Rear end ratio isn't going the change your life in terms of MPG. Towing experience (acceleration, etc.) may be improved slightly.

 

[GTyankee]

I am wondering where the noise might be coming from
AXLE BEARINGS
or
Low on fluid
or
slight possibility your rear end has LSD & needs friction modifier ?