Question: I am confused with the different gears. I have a 2007 Unlimited with auto trans. I believe I have 4.10 gears. Why did Jeep discontinue 4.10 gears in X models and have 3.21 gears. What is the difference in performance terms, mainly towing?

 

Email Chryslers customers service department and ask for a build sheet off your VIN. It will list everything the factory installed in your vehicle including the gears.

Why they discontinued 4.10's no idea. Maybe so people would buy them and pay to have them installed.

 

I believe all 2007 JKs with auto trans came with 4.10s.

4.10s are better for towing than 3.21s or 3.73s. Per Jeep.com: "A numerically lower axle ratio results in lower engine rpm and better fuel economy. A numerically higher ratio improves acceleration, climbing grades, carrying loads or pulling a trailer."

The only reason I can think of for the discontinuation is that 3.21s or 3.73s might suit the stock tire size of X's and Saharas better than 4.10s. It also creates sort of a selling point for the Rubicon, at least to customers who don't know much about gearing.

 

My guess is that they went with the lower ratios in attempt to increase their MPG rating given soaring gas prices.