Mild rant here. Doing a brake rebuild on the 70. Been about 35 years and it was way overdue. Wanted good stuff so I went with AC Delco premium parts thinking that stuff should be good. The first rotor looked real good, whole front was machined real pretty. Second rotor looked a little off. Did some measuring, sure was off. Both disc sections were thick and thin, back side had some bare casting still visible, casting off center. Looks like a real mess but the balance is off just a bit that I can tell with clean dry bearings. Guess I'll find out (in years to come) if it makes a difference.