B-26K 'Counter Invader' 64-17640 started life as A-26C 44-35896 and later saw extensive service in Vietnam. In the late-1950's, the B-26's were recalled for duty and rebuilt in 1961 and they proved to be tough workhorses.40 B-26Ks were delivered to the USAF between June 1964 and April 1965. These received s/n's 64-17640 - 17679. In May 1966 the aircraft were reassigned the old attack designation of A-26A. When they were retired in November 1969, the last active unit was 609 Special Operations Squadron. The B-26K/A-26A's were replaced by AC-130A/E's.