If I remember correctly I bought a zilla for parts from a member from the other site and it had these shims installed but they had stress cracks. I do not know if I still have these shims lying in a box or if I threw them out. I am gonna see if I still have them and post a pic.

First off, These are made from my CAD drawings no one elses, material is 7175  not the cheap aluminum, plus parts were tumbled to take away any sharp edges  that could lead to cracks, it took less than 15 mins to install these shims

7175 is a high strength, heat treatable, forging alloy. It has an excellent combination of toughness and strength, similar to 7075 alloy except that the 7175 version has superior toughness and tensile strength.