Factory Drum Brake Size?

The 9" and 10" drum spindles look much different. The 9" spindle has a "gooseneck" to the upper ball joint which comes in from the front (or back, forgot), whereas the 10" spindle "gooseneck" is centered, and thus looks shorter. Google images to be clear. The dust cap on the hub is also a different size, as I recall. Of course, if you remove the wheel the drum will be stamped for max diameter to turn.