Built by the Howard
Auto Cultivator Company. or HAC. Howard's had a prior record as a contractor to the Aust Defence Dept, being the WW2 Australian manufacturer of the
Revolver, No2 Mk1*. These were sold in a large number in an auction in the late 90's and an opinion was expressed by someone at the auction that the NSN number on the timber crates was a Centurion number. However, that said, pictures exist of the ACCO prototype trials featuring one mounted on the cab. I have never seen these fitted in service to a Mk3 or Mk4 ACCO.