The reason the double pinion bearing race fell out during disassembly is because it had spun in the banjo housing mounting. You can see the spin marks in the banjo photo. This is because the last person to have it apart tightened the two double nuts down tight instead of using them to set the pre-load. The bearings were probably locked up tight when the rear end went back in the car. Henry's 40 horses broke them loose and spun the race. I have encountered this a number of times.
The banjo should be replaced, and it is what I do, because you will have difficulty setting the pinion bearing pre-load, if you are able to do it at all. The new race may continue to spin, and the pinion bearing assembly will not be riding on bearings.
Be sure to not use an early 28 banjo that does not have support gussets top and bottom of the torque tube flange. They are prone to crack in this area, and most are already cracked at four of the mounting bolts.
It is true Henry did not put a gasket at the torque tube mounting flange. He also had oil leaks. I have been putting a gasket there for years and no ill effects have been reported back to me.
The web site of the Santa Anita A's Model A Ford club has my full library of technical articles on it and there is a couple dozen articles about differential rebuilding that is available to everyone. You are free to download and print out any of them.
Go to:
www.santaanitaas.org. On the home page click on my name to pull up the articles.
Tom Endy