Go to MLU Forum (All British Commonwealth WW2 vehicle enthusiast site).
You can find your full vehicle history in the records held by the Australian War Memorial. There are obviously thousands of vehicles so the MLU site has a lot of threads guiding you how to search the vehicle records.
I went searching for information on what I thought was a RAAF piece of plant, a David Brown tractor that had the blue paint below the grille and bits of white numbers. Eventually I got onto the Australian War Memorial in Canberra and they had no records on plant unless it had a bloody big cannon hanging off it but the then pointed me in the direction of Land Rover Australia which had some records of plant but not tractors. Guess what eles they had the bloody tanks.
Don't know if this helps but is always worth an email or phone call.
Cheers Cobba & Cobbarette
Coopernook, The Centre of our Universe.
Aus War Museum seem unfathamable to the unititiated.
Here is the link to record AWM126 which are copies of the books which contain records of every vehicle with one of those long numbers. www.awm.gov.au/advanced-search?query=AWM126
To find your vehicle you need to know the AVRN number to be able to go to the right book and page. They are only copies so you can't search by make etc.
However another route to to search the image collections. eg "Diamond T or tank transporter, and you might find a legible number - look for that in the registration books and by chance yours might be one of the same batch, identified by chassis no. Photos tend to have location and section as part of the description.
The Diamond T that were sold in the early 1970s,were basically unused at the end of WW2,and still in service when replaced by the Scammels from 1968 onward......so most of the nice condition Diamond Ts,will have the later defence rego numbers ,which are much better organized in the records.....These were on rego plates ,not just painted on bonnet sides as in WW2.........this supposes they were ever used ,and not just taken from storage and sold ,as many vehicles obviously were........the ones in use all had QRTTs,not ballast bodies.,Many sold in the 70s had ballast bodies and very dark green paint,straight out of storage to disposal..