I've been told by one of the old Mopar drag Seminar engineers that Mopar never made cast iron flywheels after the late 1940 or so, I think, only cast steel
I saw what happened to Bob Lambeck 1968 Modified Production car when it exploded a Borg and Beck pressure plate in 2nd gear around 7600 RPM, it basically ruined that car along with breaking some bones in his right foot
Sheet happens that we can't control sometimes