Ric,
Mike Cecil did a great C60X history on the old CMP site. see here:-
http://www.oldcmp.net/C60x_cecil.html#Anchor-3800. This will explain quite a bit about the use of the C60X in Australian service.
I had one of the "Truck, Breakdown (Aust) No.4"s which is now unfortunately up at Rust Hill in SA. It is still all there but spread out over the property.
When I first obtained it , it had 7.50x20 wheels and tyres all round. I fitted 12.00x20's.
Attached are some photos of it when I first brought it home fitted with an old fuel tank for fire fighting purposes and then after we fitted the original body found at Lindenow. The wooden spares box was also there and you will see it in the photos. It had a 'Manufactured by General Motors Holden" brass plate below the right hand door.
This truck rolled going down a steep road into Lakes Enterance (Jimmy's Point) and was sold as is where is. The Mount Alfred Saw mills purchased it and turned it into a timber jinker with DUKW axles. I'll post a couple more shortly.
Regards Rick.