Drawings in a Master Parts Catalog are really not a exact replication of what the actual part looks like.

My feeling is the shaft you have is the original shaft that was installed on the assembly line.

The lath machinist could of just machined a little to much off of the front end of the shaft.
Or the machinist turned a B type into a C type.
Attachments
3600 front propeller shaft.jpg (46.94 KB, 62 downloads)
3600 front propeller shaft 2.jpg (177.68 KB, 59 downloads)