For those saying it might be an '86, it is most likely not. In 1986, the High Sierra frame was TIG-welded. Only the Cimarron that year featured fillet-brazing. Also, this bike is finished in black chrome and in 1986 only the regular Sierra had the black chrome option.
If anyone has a scan of the 1987 ATB catalog spec, that would be greatly appreciated. Below is 1986.
