Drilled the D size hole through the TR coupling using my special home made drill guide. After opening up the hole with the D Drill the bolt fit nice and snug. Next i removed the % bolts from the RTone at a time and drilled the bolt hears for saftety wiring with a 1/16" drill.. I also drilled the holes into the pitch horns and slider, but dd not install the saftety wire yeat. This will be done on final assembly.