G'day prd, I think I have worked it out,sort of, going back through some old posts it seems there could be 2 belts for these, no idea why, but there was talk of an A100 belt and the A102 belt which is the GT120 belt that is supposed to fit. On googling around the only one I came up with was the 5XL but I have since found out the adjuster is not the same. The anniversary has 3 holes on both the rear idler wheels,( the pics I was looking at seemed like the hole was slotted but my mate has confirmed that the have the three holes. Hopefully he will be able to get the belt on so I don't have to drive up and do it.
Cheers Norm