Bus 673 was a MAN SG192 articulated bus with body by Commonwealth Aircraft Corporation. It operated for ACTION between January 1986 and July 1993.
673 was built in November 1979 as a MAN demonstrator at the same time as ACTION units 550 and 551.
It first entered service in December 1979 at Metro Hobart, where it carried fleet number 701. It remained there until February 1980.
From 1982 until 1983 it operated for Darwin Buslines, with fleet number 39 before moving to Brisbane City Council, carrying fleet number 997 (registration 242-OVI).
The bus was then purchased by ACTION, who took delivery on 6 December 1985 ahead of its entry into service the following month.
The bus was painted into a special livery to commemorate the Australian Bicentenary in 1988. The livery was also applied to other Government-owned buses elsewhere in the country.
After being withdrawn from service in July 1993, it operated for Premier Nowra. It has since been scrapped for parts.