The starting body assembly date on my 68 Z/28 cowl tag is 04A(April 1st week) and my VIN # is 123478N4 _ _ _ _ 5( I deleted 4 numbers for security) and according to the numbers posted on this web site, the VIN # calculates to the fact that the car was completed the 8th day of April 68. The calculations were made using the last VIN # produced for March 68 and the last VIN # produced for April 68. For the month of April 68 18,227 units were built, and using a 5 day work week there were 22 work days in April 68, this means around 830 +/- units were built per day((3 shifts). Now if the VIN # were sequencial by 1, I multiplied the 830 units per day X 8 = 6640, I added that to the VIN # of the last unit built in March 68 and my VIN # falls into that range. I do not have the origional motor to check the assembly date stamped on it which would have helped in determining the final production date. My reason for doing this is because I am restoring my Z to origional matching numbers and the only thing that is not original is the motor, as mentioned before, and in my search for the parts I have to find them with the right casting dates. The correct casting dates would be within 10 days of the final assembly date. IF YOU FIND THIS IN ERROR PLEASE REPLY, THANKS.