does the front and rear end have to have the same gear ratio? like when doing a rear axle swap does it have to match the front? also is there a chart or something the tells what axles have what ratios? thanks.

 

if you're planning on going 4wd they have to be the same. I just went through this, changing the front back to the rear ratio, someone had put a 3.73 in front with the rear being a 3.55. When I first tried to put it in 4wd, it felt like it (the GC) wanted to fold up in the middle and took some time for it to finally release.

oh, the ratios on mine were on a tag at the differential covers.

 

They have to match and you won't find a chart because axles came with many different ratios depending on vehicle and options. XJs alone can be found with anything from 3.07s to 4.56s in stock form.