General Motors Strikes ~ ChevelleStuff.Net
A major strike of GM on September 14/15, 1970 lasted for 67 days and delayed assembly of early 1971 model year Chevelles & El Caminos.
A short strike from April 1969 to May, 1969 caused a minor delay in production.
A strike occurred in late January 1968
at Tonawanda, Saginaw, and the Defiance foundries.
A strike from September 1964 to February, 1965 caused extra delays in getting a Positraction rear end for 65s. When a strike was pending it was not uncommon for outside suppliers (like engines, transmissions, etc.) to stockpile 4-6 months worth of equipment. This may account for the longer than normal 1-3 month difference between driveline dates and final assembly dates.