Hanno,
Not 10cwt - 8cwt: a Trailer, 8cwt, GS (Aust) No.3 to be precise.
You need Keith and my book on Aust jeeps and jeep trailers!
The CMP is a Chev C15A 15 cwt Battery Staff vehicle with an Australian Sunshine cab and No.2 all-steel body with valise lockers.
Mike