The VIN number is the determining item. The visible VIN on the windshield frame for US cars starts at 7114. This was a specific federal requirement.
Bill, the "model year" for Pagoda is a confusing item which has been discussed a number of times on the forum. You can check this out with the search function.
For example my 280 SL is a 1970 model year specification (that is, has all the federal requirements for the US that were required for 1970 model year cars, but was built in September 1969).
Early or late is not really a definitive term. It is most often applied to the 250 SL, since it got caught by the large changes for the US in the middle of 1967. But The VIN is the key item for tracking when different items apply - car year, title year, model year, etc. have a number of variables.
