Topic: Convertible top cylinder date codes

[Oz390]

I have what I think is a mid-66 variant convertible top frame.  Trying to nail down some estimates for some engineering changeover dates.

I have two hydraulic cylinders off it, both stamped K6 (or 6K) dyslexia and a bad memory are so fun!  Don't remember and they are not at home.  Would this be Oct 66?.  Is this a common date code format for these items for '65-'68?  Month-Year?

Semi-related question, these are the "early" style as far as I know, that used a nylon bushing between the cylinder and frame bracket.  I believe this was later removed, and the changeover occurred on the 67's, but am not sure.  Does anyone have an approximate date for removal of the bushing and the change to the cylinder mount?