Yeah, I just found out that I do need the plate number, which I haven't got.
When I'm ready I'll call the rego department.
But you're right, I tried once to find my Dad's old C12 BSA (cos I had a Vic rego number) and everyone on the phone would tell me that it was last registered in 1987, but wouldn't give me any other information.
Actually my KX was last registered in 1987 as well (as a KDX 500 though) and as far as the rego people are concerned, it never changed hands. I'd hardly use it, especially on the road, but it would be fun to do anyway.