I've taken just one as an example from the Lockheed File by Ron Cuskelly.........
A97-205 
Type: L-182-1A Hercules C-130A-50-LM
Msn: 182-3205
Call Sign: VM-JLA
I clearly remember the Caribou, CT4A and the Winjeel as also having a VM-*** radio callsign placard on the instrument panel in the same manner as civil aircraft have a VH-*** placard.
I knew I wasn't imagining this
Disco