I haven't notice those instructions before about the GM motors, thanks for pointing that out up
I was using their all aluminum dampeners until one of their tech said not to do that, especially on race motors that revved above 5000 RPM work
I now use their steel hub and 3 ring steel outer dampeners on all the motors I build for drag racing and any motor that will be revved up over 5000 RPM up

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)