Yes Northwest got rid of their DC-8-30s (1 in 1962, 3 in 1963 1 in 1964) as soon as JT-3D turbofan powered types were available and switched to Boeing 707-320Bs. Pan Am sold their DC-8-30s to Delta about 1968-1969,i.e. after some 7-8 years, one or two then reappeared in Europe freshly painted in Pan Am colours on some Delta/PanAm through-plane flights into 1971
