Cobra build no's

[Firemanpete]

I am only new to the Forum but am the owner of #254 and have been since 1986.
When I lived in Rockhampton, QLD around 1990, I ran into an aboriginal named Allen who owned a Cobra, so naturally I pulled up to check it out. I can't remember all the details but remember clearly it had a glove box plate that read the same as mine with the cobra pic,the word "COBRA", but had the word "PROTOTYPE" instead of a number. I did look at the body number and it wasn't JG65UM... , and the build date was I think late 1977.
Allan managed a pub there and I saw it regularly, its rego was 777-NNX (QLD).
I have attached a photo of it. I left Rocky in 1996 and don't know what happened to it.