I just bought my new Ram today, traded in the '07 SLT Reg. cab. My window sticker has both 3.21 and 3.92 listed on it. Is there any ID number on the axle that will tell me which ratio I have? It's an '09 Crew Cab Lonestar edition with 20s and a Hemi, if that helps any.

 

i have a crew cab Big Horn with 20's and the Hemi. mine has the 3.92's so going on the fact that the Lone Star and the Big Horn are the same thing i would assume that you have the 3.92's. are the 3.92's listed on the left or the right side if the window sticker? if they are on the right then they were part of the Lone Star package.

 

I have a Big Horn also and mine is a 3.55

 

Ivaskaj, I assume that you have the 2wd version if so I beleive the 3.21 is the standard ratio and the 3.92 is an additional option that replaces the 3.21. So it sounds to me that you should actually have the 3.92 with limited slip. If someone knows differently please correct me.

 

Your correct. He's got the 3.92, The sticker will have the basics on the left side and the options on the right side

 

There is an axle tag on right side on rear casing around the right rear tire. Just crawl under and take a look. My window sticker said 3.92 on bottom right side and so does the axle tag. I was doing that on the dealer's lot before I would even test drive them. - 3.92 LS was a must have... ( 4.10 would have been a 'nice to have'. )

 

Both ratios are listed on the right side of the sticker, 3.21 is directly above the 3.92. I have Big Horn listed on my window sticker, but Lonestar on the tail gate. Since I don't live in Texas, and the Lonestar is apparently a Texas only truck, I assume someone mixed up the tailgate logos at the factory. It's nice to know that the package is the same thing with a different name. I appreciate the input, I'll check the axle tag. I test drove a quad cab Hemi with the 17" wheels, and it was an absolute dog. Definitely didn't feel like 390 horses. It must have had the 3.21, because my bigger crew cab feels MUCH faster. Thanks again for the input.

 

the axle ratio is on a label on the axle

 

And when all else fails, your drive shaft should turn 4 (3.9) revolutions to your tires 1 if you have 392's and from the sound of it, you do. 355's would turn 3.5, 321's would turn 3.2, compared to 1 revolution of the tires.

 

or just drive it down the road and look at the tach. my truck has the 3.55 rear end and going 60mph my motor is turning 1650 rpms or 1450 rpms with the torque converter locked. if yours is higher then you have 3.92, if its lower then you have 3.21