Standard Ford and common Chrysler is 5 on 4 1/2", standard GM is 5 on 4 3/4". the latter in bot uncommon, for example Jaguars use it.
Some of either may also use 5 on 5", especially "full size" cars, and there are rare 6 stud variants, but I don't think they were used on Aussie cars.
4 1/2" is 114.3mm, a 12 thou' difference from 114mm, but don't know if they're techically interchangeable or are a rounding off for convenience, just as 4 3/4" is 120.65mm and may be a rounding figure - but make sure you CHECK if mixing them! Back in the day some vehicles changed from 4"/101.6mm to 100mm, and some people would force the wrong size on vehicles and have wheels fall off from studs being bent and snapping.
