New old stock bottom bracket shell from the 80s.  These are beautifully made, and were used by many prominent builders not just Davidson.  Bike shown is a 1984 Medici for instance.  Chain stays are 22.2, and seat tube and down tube are 28.6mm.  Threading is Italian, 36mm x 24 tpi.  I have quite a few of these.  Buy more and save.   I have lots of other frame parts too.  Tell me what you are looking for.