Hate to be picky Chuck, but P2-RDA was actually the first GV DHC-6. It was initially registered VH-GKR, then became P2-RDA after PNG started its own register. RDB was the first ex-TAA machine.
RDA was much favoured by branch managers and pilots alike, as it was a very light aircraft, lacking an autopilot and a few other goodies. Additionally, the ex-TAA aircraft had a hybrid electrical system that made them heavier too.