Black FE Special sedan

I just bought an all black FE special sedan with the red and red special interior. It was originally a Sydney car as it has all Sydney numbers and is 1956 model.
I know that these cars were primarily built for the various government departments such as Attorney Generals, Public Works, Treasury, etc, etc but this one is just a little bit different.
There are 4 big bolts (at least quarter inch) through the firewall just below the speaker grill, they dont hold anything now - but must have once.
There are also at least 8 other self tapper holes (some still with self tappers in them in the firewall
There are 2 x 5/16 holes through the subframe panel beside the radiator (2 small for heater hoses)
On the subframe skirt there is a triangle pattern of another 3 bolt holes that also must have held something. It must have been big as well, as part of the subframe skirt has been panel beaten in to fit something quite large in the engine bay.

The car at one time had a sunvisor - but not dealer fitted because it was not fitted with the proper screws.

The dash face is silver as are the bottohalf of all the door frames.

It doesn't appear to have been a taxi since there are no repairs in the roof for screw holes etc.

Anyone from NSW have any ideas what this car may have been

My thougths include maybe Police car, or Fire Dept car or something like that with a radio set fitted.

Maybe had a siren or something in the engine bay.

Ken