I know the 3.92 is supposed to get less MPG than the 3:55, anyone want to chime in on what real world differences they have seen between the two?

 

depending on if you drive more in town or highway. in town you might get better mpg but it wont be any more than about 1mpg if that with the 3.92. highway varies because of the 4 cyl mode but from what I have gathered you will get around 1 to 2mpg better highway with the 3.55

 

There really isn't that much difference. Sure, if you were driving 100% highway miles, then a 3.55:1 ratio will get better mileage, but not a huge difference. Where the 3.92:1 ratio really shines is in city driving. It actually takes less to get the truck moving so it does help on fuel a bit. Main thing you need to concern yourself with is if you need limited slip or not. That should be your deciding factor.

Personally, I've got the 3.92's and I get around 15-16 mixed highway/city driving and about 18.5-20 out on the highway. Considering I live in the hills, I'm happy.

 

Laramie: What would you say in parts it would cost be to upgrade of 3.92 front and rear, and LSD in the rear?
Sorry to hijack WIdespread

 

if you went with mopar parts then you would be looking at about 2200. If you go aftermarket then you could probably get it done for about 1500 roughly.

 

That's not too bad, on the wish list though.

 

FYI.

My 1998 Ram with the 3.92 turned around 2,000 rpm at 70 mph IIRC. I drove a 2010 in January that had the 3.92. I was reluctant to do so as I wanted better mileage an preferred the 3.55. Well I was surprised to see the tach turning 1,600 rpm at 60mph even with the 3.92. I reminded myself this new truck has a 5 speed automatic not a 4 speed and top gear on this tranny is .67.

I say get the 3.92 for limited slip reasons alone.

NC

 

deleted

 

The odometer reading is how many miles that were driven on that fuel up so far.

 

I had a 2011 SLT qc as a loaner from dealer last month when I had service and recall work done. It had the 3.55's with the hemi. It only had 2200 miles on it, ahh the new truck smell was nice ! But 0-80mph sprints, you sure can tell the difference from a dead stop off the line with these versus the 3.92.