A club member had a LL Chev something like your description..it was a ex bush fire brigade truck..it was purchased new by the brigade in 1943 . Open cab , the cab was probably custom made , but GMH could have done it as they did a lot of 'specials' for various organisations .. It was in service until the early 1980's believe it or not..it came from the Strathbogie ranges behind Benalla .. the original wartime plates were still current , with a D prefix letter . The truck had done very few miles and the motor sounded like a swiss watch .. barely worn in. It was sold by tender and it would have to be the most original LL chevy I've ever seen .
this is what many bush fire brigades used
http://www.abc.net.au/rural/content/2007/s2012052.htm
Mike