Hi John,
AC part #224955 crosses to National Oil Seal #240414. See this interchange listing. You can try and get that at any local distributor of power transmission equipment. It is a nitrile rubber lip seal, according to National. That AC part number supercedes AC #210465 per the later B parts manual. The older parts manual for the early Bs indicates this seal (210465) to be a cork washer. I can see why it was replaced with a lip seal. I hate those cork washer type seals :o).
Rod