I am still having a hard time getting the arm lengths adjusted to get the driveshaft vibration out of my 4 door unlimited with 37" Nitto's.
My front uppers are adjusted to 19 1/2" long and the lowers are 23 9/16".
The angle measured under the C's on the driver side is 3 1/2 degrees.
The angle under the passenger side C is 3 - 3 1/2 degrees.
I going to adjust the lowers to about 23 1/2 and take another measurement.

If there is anyone else running this set-up, I would really like to know what arm lengths you are running and if you just had to live with the vibration or if you adjusted it out.

 

I forgot to mention that I am running 5:38 gears. I have heard that the gear ration may have something to do with the amount of vibration that you have to deal with.

 

Currently I am running the same lift with coast 1310 shafts. However I am running 35's and stock gearing and am having no vibrations, will be moving up to 37's and 5.13's shortly so I hope I don't get any vibrations when I go bigger.

 

Try doing a cross measurement on your control arms. I bet it's not square.

 

I don't know how I did it (guess I need to quit working when I get tired) but I had the driver side lower control arm set at 23 3/4" and the passenger side at 23 1/2"
I adjusted both the lowers to 23 1/2" and it seams to have helped.
The uppers are still at 19 1/2"
The caster angle is 3 degrees on both sides.
It drives just fine.
There is still a little bit of vibration at 50 mph but goes away at 55mph.
Better than before. I guess I will just drive it for a while and see If I can live with it.
I feel like a dumbass for misreading the taperule, but it was late and I had gotten tired.