Is that quote from the 1954 Chevrolet Truck Operator's Manual or the Car Owner's Manual? I see a warning in the car manual about not towing over 45mph?
I have a 3.55 rear in a 54 truck with big tires (diameter 31.5) and it will cruise all day at 65 mph - do you expect "valve float" at 2500 RPM?
I have cruised at 70 for four hours - less than 2700 RPM. I might not recognize "valve float" but my professional mechanic friend and racing friends might have (if it was occurring).
My mechanic-friend was also impressed by the smoothness and power when we cruised for a short while at much higher speeds.
