[FC] Need some expert help

[corvanatics@corvair.org]

Hey All.  I need some help with a transmission.  I have an aluminum cased 3 
speed with the short output shaft.  I know that they are perculiar to 60 
models.  However, on checking this one, everything matches and looks right 
except the casting number on the side.  The Primer says the right number is  
6256685.  Mine says 6256675.  It is a 3 speed, aluminum cased, with a stamped 
steel cover, short output shaft and the input shaft is 21 3/4 inches long.  
Any ideas, comments, suggestions, is this perhaps a real early 60, or what?  
Would appreciate any comments.  Thanks  Bob Bauer