The Ford C4 and C6 automatic transmissions have been equipped in millions of production rear-wheel drive cars and trucks since they were introduced in the 1960s (C4 in 1964, C6 in 1966). They remained in production deep into the 1980s, when overdrive-equipped
transmissions finally eclipsed them. However, the C4 and C6 still remain incredibly popular with enthusiasts, racers, and restorers alike due to their simplicity, strength, and low cost.