As far as I can understand about the topic the TT refers to Tom Tom (BD for bass drum etc.) 9xx refers to the 9000 series which later became the legendary Recording Customs, the 14 refers to the size. The D after the 914 makes it Birch while the A afterwards denotes these have phillipine mahogany and Luan plies (that later became the TOUR series. Your drums are essentially early Tour series drums. Very nice sounding kits by the way.