Sep 2005 ---------------- cruising rpm --------------------------------------------- The FOM/3.31 in the 55 still seems to be revving too high for a comfortable cruise ---------------------------------------------- With the 3.73, 259 and auto I was turning 3750 at 75 MPH. The car LOVED it and got right at 21-22 MPG on the highway. With the 3.07's it was in the 16 range and with the 3.31 I am getting right at 19. The speed gear was correct each time and the speedo and odometer were within 2% ----------------------------------------------- 3750......?!?!?!?!? ISTR somewhere being warned that continuous running over 3500 could invite oil pumping up into the heads in a "well broken in" V8, I'm guessing you didn't have that problem, as evidenced by the fact that it's still running... ----------------------------------------------- My Champ(8E12) runs all day at 3400rpm (70-75mph). 4.11 rear axle T-98A truck 4 spd. ------------------- I'll have to do some checking (like getting the car out of the garage and driving it ) but I think that with the 3.31's in it I am now turning right at 3k+/- at 70 now. The car seems quite comfortable doing it but not as happy as it was with the 3.73 rear. It does sound about right that you are running 2800-2900 with the 3.07. -------------------------------