Leaking shaft seal in Badger garbage grinder?

Replacement seals aren't available from Badger. All their web site gives is the Badger part number (4250) with no size or diameter specs. Does anyone know of an interchangeable part from any seal manufacture?
Most garbage disposal failures (other than installation or plumbing leaks) are caused by the shaft seal. Water dripping from the bottom of the motor, breaker switch or "wrench" hole is a pretty positive indication of the problem.