My guess is you should contact Hobie Australia for this info. It looks like a different number/lettering system than Hobie USA uses here. I believe sail numbers in the early, early days corresponded with the serial numbers on most boats but in the last 15-20 years this is not the case with folks buying new sails for their boats. My boats are 1985 and 1986 and my current sail number is 52288. I think those years ('85-'86) started with 38s-41s.
Early USA boats, 1968-1974, had a 4 digit number stamped into the front pylons. It was around late 1975-1976 that the serial numbers were scribed in the transoms.
Bob

"The election is over, the talking is done, Your party lost, my party won. So let us be friends, let arguments pass, I’ll hug my elephant, you kiss you’re a $$.”
Liberalism = A brain eating amoeba & a failed political ideology of the 20th century!