I get a laugh out of reading 1970 car mags, they usually make little reference to 3.91--4.10 gears not being highway friendly. Comparing a 1971 3.55 gear 383 Road Runner to a 4.10 gear 440 6 pack Road Runner they go on to say how both cars about about even zero to 60 but 90 to 110 the 440 car is much safer at those speeds compare to the 3.55 gear 383 car.
Then the oil company have ads saying how their 260 pump fuel is like racing fuel, just cheaper and made for cooler temps, like early morning starts
