It should be a 1988 model based on the serial number in conjunction with the AccuShift and the decal style. The higher up, 1988 Sport SX was made in Japan with Tange tubing, so I suspect this is the same, though I wouldn't rule out Taiwan. The post size is indicative of Tange and the fact that the decal does not mention butting points to Tange #5 or the seamed equivalent. Since the forks are hi-tensile, the stays almost almost certainly the same material.