Now that I can see it:
was it allways yellow - build papers on your add seem to say "beige" (as well as its name, "Keith"!)
The one I remember was certainly a ragtop, but I remember it being a dirty grey/greenish colour.
If its the one I knew of, you sure have a vehicle with a bit of history there.
Further edit (following discssion with a mate)
It used to get parked next to the woodshed at timbertop. One day at the end of term, the students carried it into the woodshed and left it parked sideways between 2 stacks of firewood.
It wasnt found by the owner until after all the students had departed. He had to move about 5 ton of firewood himself before he could get it out!