Goes a little something like this....
loopy 78 to 84.
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Straight chain stay, intergrated seat clamp, 84-6
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Then the same bike for a while but with the more common tapered chainstays lasted till 91ish.
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when it changed to the pitbull brake version with the inch headset
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later varients had the inch and an eighth headset, till the Asian made ones that had the serial number on the bottom bracket