74 cj5 rear axle shims?

Hi all, I'm in the process of installing a 4" lift in my 74 cj5, I used 2.5" wide springs and have the back done, the drive shaft angle is quite severe at the moment, the kit came with a transfer case drop kit with spacers width of 1.25". I wouldn't say this will be enough and was thinking I will need shims for the rear axle, I was just wondering what deg I should get, 6 deg seems to be the norm from a few searches that I seen. I know everyone says to use steel ones so I will.

 

You may also want to check out CV joints for the driveshaft.

http://www.4xshaft.com/

 

I did the shims for a while. They didn't hold up very well. They helped a little but still ate up u joints. I ended up putting in CV joints for the driveline & new spring perches with the correct angle for the new driveline. All is good now.