I rang Vicroads last year to clarify certain things about getting a Roadworthy for a Mustang that doesn't have seatbelts
and do they have to have them.
The guy at Vicroads said that the rules are
whatever rules were in place when the vehicle rolled out of the factory in what ever year, then that is what is applicable to that vehicle.
For example: '66 no seat belt, don't quote me but I think '68 lap seat belts and then early '70's lap sach seat belts
So I said what happens when a policeman pulls you up for not wearing a seatbelt and tries to fine you on the spot?
He said what you do is you go to the Vicroads website and look up when certain rules came out like seatbelts, indicators etc:
and you print it out and when it happens you pull it out of your glove box and tell him to shove it and to learn the rules that apply,
and then you get back into your car and start laughing.
And they were his words, I was surprised
For your interest click on the link and scroll down the file to the last page and it is on the right
Enjoy
http://www.vicroads.vic.gov.au/NR/rdonlyres/6FE56EC3-FB53-4D2F-BA9F-E805C68F3DEC/0/VSI3web.pdf