Well, the saga continues... I bought 2 new bolts and it also seems the first couple threads in the bolt hole are also stripped. I guess tap and die to see how this is going to work.
It's interesting to me that the Volvo S40/C30/V50 on the same platform uses a nearly identical shock mount, but I never see people on the Volvo forums with problems due to cracking. Better quality (Lemforder?) part? Stress concentrations from the shallow notches on the top of the Mazda part?