This should answer a few questions.
Reference to the design shape is contained in a Mechanisation Board minute featured in Ventham and Fletcher’s Moving the guns : the mechanisation of the Royal Artillery, 1854-1939, p81. shown above.
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1942 Chevrolet C60L WO48 - (Workshop)
1944 F15A
1965 Workshop Platform Trailer, Binned ARN: 101-803
1967 Trailer, 1/2 ton AUST No 5 ARN: 154-748
1990 Perentie 6x6 ERV, ARN: 51-981