To tell you the truth I was just waiting for something like this....
The brothers swapped bikes... maybe
I'm not saying it's a very intelligent explanation (especially with the 3cm difference in seat tube length), but it fits flawlessly with everything else:
- E9943 is, by my reckoning, a ~June 1984 production; not a perfect spring, perhaps, but it would have made it to the September 1984 race with no problem.
- Z566 appears then (summer 1984) when the Columbus SLX... already exists.
- A photo and "race receipt" from September 1984 find their place.
- Z1701 built in late 1984 and purchased in spring 1985 is also in its place
- a couple of frames built for Panasonic (September 1985) with Z45xx designations for the 1986 season doesn't shatter either the chronology or the monthly production output of EMC.
I don't know if this is the final version, but...it makes some sense.