David,
Someone recently gave me a four speed tranny out of a '46, since it might come in handy if I needed parts for my '42. I disassembled the speedometer driven gear and removed the u-joint. I discovered the exact same part as you have pictured in the same place. I think it is referred to as an oil seal in the parts diagram and I assumed the rubber or other sealing material had disintegrated leaving this ring of non-machined metal that looks like it won't seal anything.
Kent
