With a 3.45 in fifth at 3000 rpm I’m doing 77MPH, my speedo has been calibrated. You most likely have a 3.64 so it sounds like your speedo is reading fast, I would expect 73/74mph At 3000rpm.Thanks for the stamping location. Now I know where to look to see what LSD is in my car. About 3000 RPM was 80 MPH ,and 4000 RPM was 100MPH in 5th gear.