This appears to be one of the "Wireless 1 Ton" vehicles issued to signals units early on. There are references to cabinets L.P. No's 2 and 3 etc in various wireless ( 101 and 109 set ) manuals but going by the few pics we have ,they all seem to be mounted in different locations within the ute tub. Some are sideways, others face the front..
http://www.slv.vic.gov.au/argus/0/0/...an004184.shtml
There are records on the NAA archive web site relating to wireless cabinets LP No 2 and 3 , but you have to organize a viewing down in Melbourne.
Another variation of a Ford utility with wireless
http://www.slv.vic.gov.au/argus/0/0/...an008133.shtml