The pre october 79 were not galvanised, and all to often rusted to pieces... So keep a wide eye open for cancer.
The advantage to a pre gal moke is that the parts are ALL interchanable,,, every bit of it. The Gal bodies, well they aren't as much, they have a lot of different parts on them.
The rear tank is a Bug Eyed Sprite tank out of and A/H... I reckon it would be cool it you could put one of those in AND a side tank,, you could drive half way across the country in any direction
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The only downer with the early models is RUST,, especially if its from a coastal area, you can garantee that some yuppy has had the romantic idea of driving it thru the sand at the beach at least once

(once if your lucky!!)
Apart from the rust, I reckon that the the advantage with parts availablity is a huge bonus.
But, look, you don't
need to buy a genuine cali,, they cost more, and you could easily get the cali parts you like and fit them to a base model... almost everyone has done it.
Growing up I have seen probably 500-600 mokes, and about 400 realy up close and personal.. and of them, only about 6 were really genuine ridgy didge. Its almost safe to say, that the most of the time, the difference between a cali and base model is ONLY the body number... everything else you can buy for them.