[ford38v8]

According to Wagner, the first digit is year, second is engine, third is the last digit of the wheelbase. Thus, 817T is your designation. The 81T is your cab only, with body numbers of 235 and 260 respectively. There is no conflict in that, as the cabs were the same regardless of wheelbase.

I have no information on the tonnage rating plate you have, nor wheel sizes, given that the Chassis/Cabs could have been fitted with a platform or a stake, or delivered bare to a custom fitter.

Your trucks would have been of Canadian manufacture, delivered and fitted in Australia. I assume right hand drive. Although I cannot confirm Canadian manufacture of the engines, those numbers are not U.S., so it is logical to also assume Canadian.