2008 Arctic Cat ThunderCat ATV Service Manual, Page 119Get this manual
6Install the shift fork assembly making sure the fork leg is facing upwardApply small amount of oil to the gasket; then install the gasket
8Install the proper shim onto the ring gear spider assembly making sure the chamfer side of the shim is facing toward the ring gearInstall the ring gear in the housing; then install the outside shim with the chamfer side of the shim toward the ring gearNOTE: The spider and ring gear assembly must be replaced as complete unit