Based on the PA-31 Cheyenne I and II series, the Cheyenne IIIA was referred to as the PA 42-720. It is powered by two 720 shp PT6A-61 engines. The Cheyenne III has 720 shp PT6A-41 engines. The III-series cabin was longer than the Cheyenne I and II series. Externally, the III is distinguished from the I/II by its tall, T-tail. The Cheyenne III series typically seat six or seven and include an aft lavatory.