On a more serious note, I would ask Kevin Marti for help. I looked at the General Statistics in his Numbers book and see that 63D is blank for 1969 indicating to me that NONE were made (page 8, Mustang, By The Numbers).
On that same page, 65D designates the use of Decor Bench in the hardtop body (not in sportsroof nor convertible).
Obviously, something unique going on here but I was under the impression that any RPO would be in the Stats that Kevin has and the Mustang E is for sure a regular production option.
On edit~fixed typos