The 67 model year is very interesting to say the least. There are versions of a 67 type 1. Early is for car made from Aug-Sept 66, Oct, Nov, Dec are mid year and January-July 67 are considered late 67's. There are changes which took place during the model run which drives the Early, Mid and later version. I'm not exactly sure when the seat release was moved up to the side of the seat. However, I do have a couple of references which I will check to see if there is any information available. My 67 converible was made in August of 66, and the Sun Roof was made in early Sept of 66.
In the states the difference between a 67 seat with the release on the side and a 68 seat is the 68 seat is taller and has a build in head rest. Which was one of the changes VW made for 68 to improve safety. :wink: