The Special tubing was used in '85, at least here in the states, and was used on 6 different models. Only the top three had a chromed chain stay. It would be almost impossible to determine which model it was unless the original parts were still on it.
I agree the fork is most likely a replacement for some reason. It almost looks like aluminum.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk