Nice build!
Your MX Leader does have the chainstays in the old-fashioned way: flattened and attached to the side of the seat tube (I'm sure there is a proper word for that). Later they became 'fastback': round and attached at the back.
Also, it doesn't have the eyelets at the front of the headtube to hold the shifting cables and prevent rub. Those were also added in the later version I think. Or was this an option, just like the number hanger? Not sure when these small changes were introduced but it was before 1990.
Never seen the paint scheme either, and it just doesn't look "right" to me: the Columbus sticker overlapping with the yellow line in the seat tube for instance. Maybe it was a custom order?
I do have one that has the dark green as part of a yellow/red scheme, so definitely a color Merckx used.
Hope this gives you another piece of the puzzle.
Last edited by stevenc; 06-27-11 at 01:51 AM.