New Rear Gears

I'm trying to do the same thing to my Cuda since I put the bigger wheel and tire combo on the back last year my actual ratio has got to be somewhere around 2.9 so I am loking for a 3.91 chunk to swap in and out with the 3.23 I have when I'm not driving too far on the highway .Either that or a 3.73 that I could probably just leave in for the highway , 28 inches is quite a bit bigger that the 245/60/14 I used to run .