Hi, I'm restoring an '07 6-speed manual limited coupe. Hoping for experienced input, concerning a final drive swap and mod. I would like to replace the stock 327 final drive gear set with 307 ratio for MPG and top cruising speed increase. Hopefully I could locate another Crossfire or MB vehicle with the 307 ring and pinion that are a direct fit for my housing, IF I knew which models to target my search. I know there will be low end torque reduction and the need for speed-input ECU programming but that's what I'm after. It will not be used as a race car. Given the low first and second gears of the NG370 trans, and a quality LSD, I suspect it will still be quick, stable, faster on the long straights and yield better HWY MPG. I could also reverse the whole process anytime if desired. Any and all comments are welcome.

 

Plenty of information using the search box upper right corner, click the threads just to the left and then the google option.
LSD can get expensive. If your just cruising you don't need it.
In a nut shell read post #4 in this thread: rear differentials

 

With the 6 speed you do not have a TCU((transmission control module)) so the swap is easy. U will need a srt-6 yoke as the limited and the srt yoke are different size.
so your driveshaft will not work with a 307 without swapping the yoke,, but if u swap the gears into your housing u can use your limited yoke . the cost to swap the gears woulf run between 5 and 700.00, where buy a 307 out of a srt6 and swap the yoke(use your yoke from your limited.
Just so u know i do have a 307 diff $150.00 + shipping and i have a limited yoke that i would throw in
I is a direct swap except for the yoke,,, the other way would buy the rear 1/2 of a srt-6 driveshaft, and i raced a crossfire that way as both driveshafts are balanced 0.
,,my way of install takes ne less than one hour as i have swapped about 20 rear ends so far in just crossfires.,, it should take u or your Mech. 3 to 4 hours, what ever way you go good luck, any problems or questions pm me. jim

 

sorry i meant to say to run a 307 rear in a limited ,you need to replace the yoke on the srt6 rear, to the yoke from the limited, as the yoke is smaller on the limited
and the yoke on the driveshaft is smaller on both ends of the limited... swap the yoke (limited small yoke) on to the 3.07 and install....
This yoke swap can be done without a tear down of the rear.
there is another way without tearing down either rear end that is to \
use the rear 1/2 of a srt drive shaft,, they are all balanced 0 and if you do not have a good mech to swap the yoke YOU WILL GET A HOWL FROM YOUR REAR!