Mike,
I think the Cummins bolts were made by Kamax and the grade is 12. 9 (metric grade designation) these are high strength bolts. Might try searching on Kamax. The other ones are grade 10. 9, also high strentgh but not as high as the 12. 9's. Maybe someone can add to this. We see 12. 9's on the Cummins flywheels during R&R and for example the Ford's that we have worked on use 10. 9, don't start drawing conclusions, its the number of bolts, grade, size, thread pitch and torque that create the compressive sandwich that holds this stuff together.