The United States Air Force (USAF) however, emerged as a buyer for the design, purchasing the aircraft for the Credible Chase programme as the AU-24A.

This was the gunship version of the Stallion, with a PT6A-27 680 shp (510 kW) turboprop, equipped with an M197 three-barrel 20x102mm rotary cannon mounted in the left cargo door.

[2] Of the 18 aircraft purchased by the USAF, fourteen or fifteen were eventually delivered to the Khmer Air Force (KAF) between January and November 1972 under the Foreign Military Sales program for use in border surveillance and counter-infiltration roles, where the threat of encountering anti-aircraft fire (other than small arms) was minimal.

[11] In the final months of the Cambodian Civil War, the KAF employed their AU-24A mini-gunships in night bombing operations against entrenched Khmer Rouge 107mm rocket positions north of Phnom Penh,[12] but after virtually expended their entire ordnance reserves, three Stallions escaped on April 16–17, 1975 from Pochentong Air Base flown by their respective crews to safe haven in neighbouring Thailand.

[13] The Khmer Rouge did manage though to salvage intact nine AU-24A mini-gunships for the Air Force of the Kampuchea Revolutionary Army (AFKRA) of the new Democratic Kampuchea Regime, although poor maintenance and a chronic shortage of spare parts ensured that only one of these machines was still airworthy when the AFKRA was neutralized by the People's Army of Vietnam (PAVN) in February 1979 during the Cambodian–Vietnamese War.