It's a mid-'50s Saginaw 3-speed, likely from a passenger car. Page 2-2 in this PDF catalog shows the case and tailshaft housing (extension) numbers given. From the casting dates (if that's what those other numbers are), it appears the case is '56 and the extension is '55.


Curt
----
1953 Chevy 6400, 1957 Chevy 2dr Sedan
--"Mediocrity is easy, the good things take time"