amx1397 and i have done it in my srt6 and it runs great ,we can supply a turnkey setup that bolts into any crossfire srt or na with out any modification to the car . it can be returned to stock by putting back original parts there is a limited supply of these new differentials after that we have to use used ones.we also supply a modified tcm so no limp mode ,we are working on a wavetrack for this setup i have over 1000 miles with no problems .contact amx1397 if your interested it makes a big difference in acceleration. there also other ratios available setup 3.64 and 2.87.

 

This was the first car we installed the 3.90 ratio rear ,now we have another and this one is a modified srt6 ,,will be going to a drag strip soon as the track opens in Wisconsin and my car will have a 3.90 in it soon, and will also run at a track.
this is a bolt in mod, you get the differential, open gears),TCU and the bolts that make the change,, the srt6 requires one extra part ( yoke part)
the cost for the limited is $1599.00 for the srt 6, $1799.00 ((price as of April 2022))

 

So no one else need look it up, the factory SRT6 differential gear is 3.07:1. All other Xfires are 3.27:1. Manual or automatic makes no difference.

 

Yes but , we have now different ratio 's to give the crossfire the boost or gain mileage we have a 2,87, 3.07, 3.27 3.66 and 3.90. I am offering the 3.90 at a reduced amount
of $995.00 for the TCU and the diff with 3.90 gears,, this can be swapped in about 2 hours ,,yes it is a bolt in. this set up in a limited will make it 1/4 second(on paper) slower than a srt6 where now it is about 1 full second slower than a srt6,,, I see post how to make a limited faster well this is it. My V8 with a 3.45 runs 10.55 @ 132,, with the stock 307 it ran 11.0 @ 121. and all your parts you remove ( the 3.27 diff and tcu(for auto) you can put back when you sell. For std shift crossfire I can do $800.00