High friction diamond-infused shims now available for the 4g63 6-bolt & 7-bolt drive flange. 
These fit both automatic and 5-speed applications. 
This newly available technology increases grip of the joint by a factor of 3-4x bare metal surfaces. 
This shim is installed between the crankshaft and the flywheel/flexplate. This adds safety factor against the joint slipping in any build and is critical in high power and high rpm builds. 
Thickness: 0.005" 
This technology surpasses the capabilities of any previous options for keeping the flexplate or flywheel to crankshaft joint from sliding. 
We recommend this for any applications above 500ft-lbs torque or above 9000rpm.