The others being the Victa Airtourer (168) and the Government Aircraft Factories (GAF) with 170 twin-engined N22 & N24 Nomads.
PAC's predecessor, AESL, derived the CT/4 from the earlier 4 seat prototype Victa Aircruiser, itself a development of the original Victa Airtourer two seat light tourer, 172 of which had been built in Australia from 1961 to 1966 before the rights to the Airtourer and Aircruiser were sold to the New Zealand company AESL, who built a total of 80 Airtourers at their factory at Hamilton in the 1970s.