There are four shims two widths and three thicknesses. The two narrower shims are used for installing top gears and the two wider shims are used for the removal of the top gears using the RT-HO gear press.
When installing the pinion and the driven gear you will use the narrower shims. The .010 shim is for the pinion gear and the .005 shim is for the rear driven gear. When pressing the gears on make them snug and then pull the shim out. This will give you the correct spacing every time.
You use the wider shims along with the RT-HO gear removal press to remove the top plate gears. The wider .015 thick shim is inserted just under the top plate. This shim is pushed so that both ends of the shim rests on the RT-HO Tool. This will provide the top plate the support that is needed to reduce the flex when pressing the pinion or driven gear off.