I just went out to the garage and disassembled the oil pump.  Upon direct
examination of the parts, it is apparent that the little 'ring' in the block
is, in fact, a pressed-in sleeve that performs the function of centering the
oil pump shaft in the hole.  Any *sealing* function provided by this
superfluous in comparison to the seal provided by the machined surfaces of
the block and oil pump body.  This is a part that a machine shop might
replace during block reconditioning (but I doubt it, unless it showed
obvious damage).

The oil pump body and its engine block mounting surface are finely machined,
eliminating the need for any type of gasket or sealant.  The original
question was whether or not there was any type of gasket required to seal
the oil pump to the engine block.  There are none.

I suggest that out of courtesy for the rest of the members of this list, we
conduct any further discussion about the function of the pressed-in sleeve
off-list, via p-mail.

Mike Snow