CAMS decided to blindly follow the FIA and introduced a five year age limit on belts. (CAMS is supposed to be our representative to the FIA and is not supposed to be the Australian arm of the FIA)
After a lot of negotiation they backed down after they set up a safety research committee to look into the effects of age on belts. The committee found that there was very little effect so CAMS has changed the rules. (one member of the committee was the bloke that invented the six point harness in the first place, it was his good work that led to the overthrow of this stupid rule)
I don't recall what the new rules are but they are not black and white, they still have various shades of grey in the rules.
You need to look up the current CAMS manual and try and find the CAMS bulletin that covers the change.
You will also need to carry the copies of the rules and bulletin to show the officials. They will probably still not believe you as they flick through their 2005 edition of the Manual.
I have very little time for CAMS. (actually none at all in the past ten years)
They are an incompetent bunch of fools that think they have a god given right to tax motorsport out of existence.