LCA Length for 5" lift?

A buddy of mine put a homebrew 5" lift on his XJ.
He wanted longer LCAs, & I had a home-fabbed set from parts unknown laying in my garage. He threw them in & they seemed to work, but we're not sure if they're the right length or not as we have no idea what the original creator was building them for. (they might be too short or possibly too long?)

Does anyone know the eye-to-eye distance on LCAs for different amounts of lift?
Does anyone know the length of uppers to correspond with the LCA length?
Is there a mathematical formula?

The reason for asking is that he has a slight vibration that occurs while driving from 35-55 mph. We put a TC drop on it & it still did it so we took the rear driveshaft out and drove it & it still does it, so we're assuming it's from the front end? It didn't have this vibration when he had a 2.5" lift.

Lift.......LCA dec.......LCA fract.....UCA dec.......UCA fract.
Stock........15.75.......15 ¾........15.00............15
2”.............15.92.......16............14.88.... ........15
3”.............16.09.......16............14.92.... ........15
4”.............16.33.......16 3/8......15.03............15
4.5”..........16.47.......16 ½........15.11............15
5”.............16.62.......16 5/8......15.21............15 ¼
6”.............16.97.......17............15.44............15 ½
7”.............17.36.......17 3/8......15.74............15 ¾
8”.............17.81.......17 ¾........16.09............16
9”.............18.30.......18 ¼........16.50............16 ½
10”...........18.82.......18 ¾........16.96............17

rstarch345 said:

Lift.......LCA dec.......LCA fract.....UCA dec.......UCA fract.
Stock........15.75.......15 ¾........15.00............15
2”.............15.92.......16............14.88.... ........15
3”.............16.09.......16............14.92.... ........15
4”.............16.33.......16 3/8......15.03............15
4.5”..........16.47.......16 ½........15.11............15
5”.............16.62.......16 5/8......15.21............15 ¼
6”.............16.97.......17............15.44............15 ½
7”.............17.36.......17 3/8......15.74............15 ¾
8”.............17.81.......17 ¾........16.09............16
9”.............18.30.......18 ¼........16.50............16 ½
10”...........18.82.......18 ¾........16.96............17

Click to expand...

Thank you VERY MUCH!