Here are all the 67 dealer items I have and it looks to me like in 68 & 69 is when the "carpet" was added to the wheel house area and only with the aforementioned decor package...also (in 68 for sure, 69 probably) there was carpet added to the back seats to all decor package cars. Another oddity seems to be the exception to this back seat thing is with white seats... They seemed to always be vinyl.
