i'm wanting a set of 3.91 gears just thought i'd ask around before buying a set new

my forum for my crown vic has a section for parts for sale we might have one as well but I havent found one yet.

as far as i've learned that the 3.55 and 3.91 were the two optional gears i'm looking for a pair of 3.91 so it would compensate for the 35" tires as far as drive train strain goes for towing and such and bring my fuel mileage back to a point better than when i had the 32"

and what big break options do we have for a 2005 ram quad cab hemi

 

If you're going to upgrade your gears, maybe consider going 4.10 or even venture to go 4.56 with 35's. If you're doing a whole rear gear swap, 3.92's wouldn't be far off and would be an easier swap (another 9.25 rear assuming). I have stock 32" with 4.56 gears that I upgraded from my 3.92 gears, and absolutely love them, mainly because I drive in the city and when I'm on the highway, I'm usually towing the TT.

 

We have a very large "Classified Section" here on DodgeForum.

As far as the gears, I had my original 3.92 right up until around Christmas when I sold them for $150 for both front and rear sets.

I went FROM 3.92s TO 4.56s when I installed my lift and 35" tires. IMO the move from 3.55 to 3.92 is not cost effective for what gains you'd achieve. I'd look to install at least 4.10s, but with the 545rfe transmission that essentially has two overdrive gears, you'd be best served by 4.56s with any tire over 33"...

 

well my stock gearing with the 33 inch tires was my best tested overall mpg with a 8% over size tire from stock, so with installing the 3.92 it would bring me back to that optimum 8% over size of adjusted gear for the tires plus make it so that the tqconverter will lock at 45mph road speed instead of 56mph while i'm driving on the back roads, now i do agree with the 4.10 witch will relive the drive line strain back to the equivlant of stock size tires but will bring me away from the optimum tire size to axle ratio to keep me locked in gear at 45 with out getting into that next gear that kicks in at 50mph that every time it down shifts from that it always goes two gears down and is annoying as heck.

 

and could you set up a link for the classified i still don't know my way around here

 

I went from 3.55 to 3.92 with an axle swap to a newer set of diffs. I hardly notice a difference

 

You hardly notice differance in power or mileage or RPMs ????

 

https://dodgeforum.com/forum/parts-sales-45/


You need 3.92's. That's what the 3rd gen Ram option, not 3.91.

You will actually gain a little MPG under 60mph with 4.56 over 3.92 with 33" tires.

 

Hardly notice a difference in power, mpgs, or RPMs at all lol. I just went to 3.92's to put in a slightly better LSD in my rear diff that had grenaded