You have a 'Truck, 3 ton, Derrick', Army Registration Number 161942.
It was written off by Board of Survey from 2 Base Ordnance Depot on 5 January 1961, and would have been sold at auction shortly afterwards.
The engine number was the key.
Interestingly, the previous serial number (146477) was an RAAF GS vehicle, while several around that, for example, serial 146474, were the RAAF version of the Derrick, called a 'Crane GP', so it would seem your truck and several RAAF 'Crane GP' were all assembled by Ford at about the same time, and farmed out to both the RAAF and Army.
Regards
Mike
