This mystery comes to me from BRIO and Thomas collector artheathen. This track piece is made from beechwood and measures 73mm long. The mystery is, where did it come from?
In the BRIO system this track would bear the ID "C3" since it is a 73mm straight with female connectors at both ends. Almost, anyway, since the A3 track is 72mm and not 73mm. BRIO has not, to my knowledge, ever produced such a piece and track A3 did not appear until 1998. By then BRIO was not only stamping it's track, but had also long been chamfering the grooves in the rails, as well as the throat of the female connector. There's no stamp, and close-ups of the end show very rounded rails, and a straight cut at the throat.
Even in the early days of BRIO track production there was not, to my knoweldge, this large rounding of the grooves. The rails were either cut straight, or had a very slight rounding or chamfer. The rounding in this mystery piece more closely resembles that used by Jesse's and Orbrium's track manufacturer, except that the quality of this track is much, much higher.
In fact, this track piece is so well made that I really don't know what to make of it. I'm 90% sure it's not a BRIO piece, but BRIO did manufacture custom pieces in some of it's vintage sets—the Harbour #31405-40 comes to mind—so I'm not comfortable going that extra 10% and proclaiming it with absolute certainty. But I am skeptical.
Have any ideas? Let me know.