As it seems that this has come up a lot in the past few weeks, I figured I'd make a post on it for future reference.

This is a list of the desired control arm lengths for the lift height you have. Measurments are taken from hole to hole on the control arm. This is the same for both XJ and MJ over all years.

LCA = Lower Control Arm
UCA = Upper Control Arm

Stock
LCA - 15¾"
UCA - 15"

2"
LCA - 16"
UCA - 15"

3"
LCA - 16"
UCA - 15"

4"
LCA - 16 3/8"
UCA - 15"

5"
LCA - 16 5/8"
UCA - 15¼"

6"
LCA - 17"
UCA - 15½"

7"
LCA - 17 3/8"
UCA - 15¾"

8"
LCA - 17¾"
UCA - 16"

9"
LCA - 18¼"
UCA - 16¼"

10"
LCA - 18¾"
UCA - 17"


For 1/2" lifts take the difference from the one above and below. So for example a 4.5" lift would be LCA - 16.5" and the UCA - 15".

I don't advise running short arms on anything over 6", but the measurements are there if you want them...