As an endurance racer, Posey appeared at the 24 Hours of Le Mans 10 times (1966, 1969–1973, and 1975–1978) and finished in the top 10 five times.
Como piloto de resistencia, Posey participou nas 24 Horas de Le Mans 10 veces (1966, 1969-1973 e 1975-1978) e terminou no top 10 cinco veces.