Long time Ford owner, just picked up a new 12 Ram qc 4x4 5.7 Hemi. I traded in my 2010 STX F-150. Trying to figure a few things out about my new truck. How do I know what rear axle I have? I'm looking over my window sticker right now and can't seem to find it. I do have the Anti-spin rear axle.
My last Dodge Ram was a 98, big difference with the new one. Also how big is my fuel tank?

 

I believe there should be a sticker on your rear axle that refers to the axle ratio. I know on my 2010 Sport my 3.92 axle was also called out on the window sticker.

Rob

 

Hope you like your new truck.

I just think the Ram looks better than the Ford.

And I can't possibly be wrong!

 

A good rule of thumb, 17" wheels=3.55s, 20" inch wheels=3.92. No guarantee though. Enjoy the new ride!

 

Pics???

 

It is almost certainly 3.92 gears and the fuel tank is 26 gallons unless the optional tank was put on there which would be on the sticker. The optional tank is 32 gallons. I hope this helps.

 

I'll have to check the axle. I appreciate it.

Also the 26 gallon fuel tank seems right, big change from the 36 gallon the F-150 had. Anyone know how many gallons are left when the low fuel light comes on?

I have 2600 miles on the Ram, had it about a month, I like it. I agree the Ram is better looking than the F-150.

Not real good at posting pics. It's just a white 4x4 Quad cab with 20's.

 

The gear ratios are 3.21 and 3.55 for the open differential and 3.92 for the posi and 4.10 with the posi on the R/T model only.

 

Islander- when did Dodge start that, my 2012 CC4X4 has 20s with the 3.92 open diff and my 2005 QC 4X4 had 17s and 3.55 limited slip. Just curious.

 

Tire/wheel size is not a good indicator of axle ratio, in my experience. There are tons of SLTs and Laramies out there with 20" wheels that have the more typical 3.55 ratio. At least in 2010, the 3.92 axle was an upcharge so it was not often ordered by dealers for standard inventory, at least here in MN.

On the 4th Gen RAMs the 3.92 has been a limited slip diff. The 3.55 and 3.21 are open diffs. This was at least true through 2011, though it is possible they changed for 2012 if you know yours is a 3.92 open diff.

Rob