Reply from ACME forum .
S8T 520 is the same as 8T15187 so any literature for that 8T S/No is correct for your machine and would have been what literature that would have been supplied with it when delivered new.

Parts Book, Form No 32644.

Grey Operation and Maintenance Instructions, Form No 10492.

Yellow No12 Motor Grader Servicemen's Reference Book (SRB) Form No 30124 should get you there for the grader section.

Yellow D318 SRB Engine Book, alas I do not have the Form No for that as my copy is missing the front and rear few pages that has the Form No on--my 1950 List of Instruction Books does not list the D310 series engines SRB's. as they likely did not come out until around 1953.
Steelweld history is in my crashed computer.

RichardT
Found this during lockdown reading-
www.hcvc.com.au/forum/oldjunk/6171-cater...r-12-grader?start=10
Few years old .
P3 or P4 Reply #68343 has some USA contacts for parts, if they' re still around.
Good luck

Hopefully this works Thanks to another of the ACME forum members . A link to workshop manual

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Another reply this morning .Built `1954.

I owned and operated a Cat 12 Grader, which was an S8T, built by Steelweld in Australia for about 18 years. It's original Serial Number was S8T480. When I bought it first, I was told that the updated computer listed number was 8T14806, that is a 1 in front and a 6 at the end, and drop the S. I always used this number to order parts, but this may have changed since 2008 when I sold the Grader. The grader was bought new by the Wambo Shire in Dalby, and I got it from Tillys in Toowoomba. Can you PM me if you are still looking for a book. Kav.

Hi Ianoz,
Sorry link does not work, you need permission to open it.