The stickers were first introduced on the 1978 Series 1 “Series Special”. This also happened to be the first year the X1/9 was sold into Australia. As RHD versions only started to become available by mid-1977. Each dealer was given a batch of stickers to place on the car at the dealership or the buyer would get the sticker and place it on the car themselves. This means there is no relationship from sticker to VIN. The only relationship is the dealership itself. The stickers continued to be placed on X1/9’s till late 1981 I would say only by one or two dealers as you don't see it often on the later models. This was probably old stock of stickers as they made more sticker numbers then actual Series Specials imported.
This sticker is on 1978 Series 1
This sticker is on 1979 Series 1.5
This sticker is on 1981 Series 2