If its for a R80 G/S (NOT the later GS) then it WILL fit the ST.
as the subframe, tank, seat etc are exactly the same on the ST as on the G/S.
... the later GS ones (no slash) will fit...sort of, but will leave a gap at the back of the tank, and will look crap.
If you get one, and decide you dont like it, can I have first dibs to put it on my ST ? (oh, and buy it with a black cover or it'll look shite on a ST IMHO).
and when did you get the ST?.... and Pictures, we likes pictures......