Woody, my aircraft, saved my young arse more than once in Vietnam. The first production Skyraiders were all designated as AD from 1 to 7. the AD-4 was given a more powerful engine, the -5 was widened to allow a 2 seater version (AD-3N a threeseater and the AD-5N was a fourseater). The -6 had upgrades to improve low-level bombing and the final -7 was given an even more powerful engine. The last Skyraider was built in 1962 at which time all existing planes were redesignated an A-1D through J, the old -1 through -7