64 -70 Plymouth Production Numbers
Sorry I have "not" been around sence my 69 got sold, however even though this post is old..I remember that I had the same questions about mine as you do. My 2 door had (273, bucket seats, front and side chrome window trims) like it was a package deal or something, however I couldn't find anyone at all thoughout my five years as owner that could find a way to go further (without paperwork) Talking to some, agreed that Valiant/Signet didn't have a hell of alot of 4 speeds. Not 100% sure but my bets is that yours was one of thoses 4 speed ordered options.