Installed the prop governor bracket under the cylindert 4-6 crankcase mounting bolts. While tightening bolts, I noted that BOTH bolts would simply spin and not tighten. That is not a good thing. I pulled off the engine mount and found that both case bolt threads had been stripped clean. See photo. I obtained some helicoils, drilled, tapped and installed helicoils. Replaced engine mount with prop governor attached.