Well, this talk of gauges is quite interesting, which make me like to ask, at this point,is Australia really had much of a difference when talking in financial terms ITTL (since troop and material wise they are in a better state), and referring to the question that expedite this talk in the first place...
Perhaps Britain ITTL with realise how much of a drag having multiple gauges is, and encourage them(?) (perhaps with generous loans on offer) to start converting to a single gauge?
Does Britain really had a say in regard to this, especially IIRC the railways itself is unders the state's goverment jurisdiction instead of the federal goverment, which probably IMHO meant at this point in practice, the British had less of a influence in regards to
Australian railways than even... the railways at the
Dutch East Indies (since those are mostly compatible with the FMSR)
Perhaps I missing something, and actually the (inter-state) rail traffic in Australia ITTL is higher than IOTL, so the break of gauge issue is more prominent ITTL, but I haven't notice any difference in terms of the potential usage (other than perhaps the increase in Australian tank production and the aforementioned update, which the impact of the latter could only be limited to NSW). So let me know if I forgotten something (again).
I think the gauge issue will be resolved quicker ITTL, but whatever it is, those will be mostly in the hands of Australia and Australians alone.
P/s: And if the influence of Britain in regard to this is actually still large at this point (in which case I think this influence will go both ways), and with the rail traffic is increasing, perhaps this could necessitate an earlier and wider adoption of
SCOA-P wheels not just in Australia, but perhaps even in the other parts of the Commonwealth.