I'm going to give this group a shot. It doesn't look like it's very active though.
I'm in the middle of a restoration of my A. I broke a bolt off in the rear axle, hub to axle. Tried to get it out, tried to drill it out, no luck. Ebay to the rescue. I got a replacement. The problem is, the final drive Bull Gear's splines don't match up with the axle splines. There are 2 possible scenarios I can speculate happened. 1) the axle I got isn't from an A. It looks exactly the same though. 2) There are 2 (or more) iterations of the axle/gear combination. That is, possibly an older axle won't fit a newer gear. I can't find any information on the later however. The parts manual doesn't indicate anything about model years being different for the A, only B and BN (and AV too). Before I attempt to replace the axle, and possibly end up in the same boat, I wonder if anyone here knows anything about this.