912 ULS Checking of propeller gearbox

Does anyone have blue prints or recommendations for a jig like this?  I work for a flight school and we are coming up on our first gearbox check and overload clutch check on our 912 ULS.  Needless to say, reading this thread is making us a little weary at producing an incorrect jig and bending the engine mount.  If there is another way that is easier, I am all ears.