No idea. Search turned up not much as you probably already know.
But if I had to guess, it could be great news or bad
.
One potentials leads is the
RD-M511 Deore series.
Another lead is the
Tourney. It's part number is RD-TY18. Maybe this one falls below that?
It would be great if it were an older high quality part.
Good luck finding what it is.