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