G'day Folks
A lot of the auxiliary equiptment fitted to Aust military vehicles was supplied by tender, which was renewed from time to time, so it depended on who won the tender as to whom supplied the equiptment, also the manufacturers varied/changed their products over the years,Hella beacons being a case in point, some early ones will be very different to later units, as will "Hella Australia" differ from "Hella Germany" as source of product.
This was also governed by the particular person/persons inside the directorate,and price and availabity of the product,also the particular requirements of the Area of Operations and Command at the time.
Hope that is of help
cheers
