Sometime in late 65/66 a change was made to the rear side rail. A small tab was added and a rubber seal applied between the rear rail and the intermediate rail.
Its an odd item, all I can figure is it was to cut down wind noise, as it faces forward and sits up inside the top.
early 65 (left) "later" (right)
Foam tab applied as a test.
Area where it would be installed (foam not present). Odd as it would just sit on top of the side rail facing forward, so not a waterstop, thus my thoughts it was wind noise at the gap.
Can folks confirm known build dates in 65/66 to try to nail down a range for when this change may have occured? I have a change date on the rear rail of 4/1/65 and think this was applied at that time, but confirmation would be good if anyone can provide info on a car of about that build date. Or if anyone has a 'late" 65 top without stud/nut cable and without this tab, this would show two chagne levels, or if they both occured at the same time.