For those of you with a '91 or later 750iL, I'd like to know for reference what your RPM's are at 70mph/113kph in the highest gear/lockup. The '91 and later models were fitted from the factory with the 3.64 differential. My '90 with the 3.15 sits at about 2000rpm at 70mph/113kph. I'd like to know what the difference is between the two differentials.