Transmission Slippage

["Alan St. John - Citizen Action" <phoenix@domain.elided>]

OK all you automatic tranny gurus, here's my question: what are the most
likely causes of transmission slippage?  The vehicle in question is a '67
800, and I'm told that it slips when it gets warm (this is not my Scout,
but it might be soon).  I'm assuming of course that the current owner has
ruled out fluid level as a cause, but I know little else about his
troubleshooting efforts or other symptoms.

Thanks,

Alan St. John
'68 800