Reply to "Am I the luckiest guy in the world?"

JFB, stock ring gear bolts have been breaking since the Pantera was still in production. We THINK its because the stock ZF bolts are ISO gr-10.8 (about gr-8 SAE) and are too hard and brittle for the job. U.S gr-5 bolts are much tougher and more ductile, which is what's needed with impact stresses like the ring gear experiences.

In addition, the stock bolts are serrated under the heads to 'dig in' and act as locks, but the surface of the ring gear is too hard for that to happen, so the serrations only act as surface-area reductions that contribute to loosening. SAE bolts are not serrated and most have drilled heads for aircraft safety wire as a further deterrent to loosening.

Since 911 Porsches use the same ZF-design differential, their second- generation ring gear bolts are not serrated under the heads and are often drilled for safety wire. You can take one of your stock ZF bolts to a race shop in Germany and ask them what they think. They will likely have spares to fit.