This is a used tail housing taken off of an aluminum 2 speed Powerglide transmission.  I couldn't find any part number on it and it's been in my barn for so long that I don't even remember where I got it.  If you know of a way to identify the year and/or model please let me know.  I don't see any cracks or any other damage.  The threaded hole where the speedometer cable connects still looks to have good threads.  Please contact me if you have any questions and thanks for looking.