Bad Seal/O ring or gasket Alpha gen 2 drive?

[fen-isl]

Hi guys, was putting out drive back together tonight, and notice what looks like remnants of an old rubber seal/O ring or gasket, in the exhaust passage for the shift rod assembly, Looked in mercuriser manual and couldn't find any reference to it, If some one has a merc part number that would be appreciated. Please see pictures
1996 mercuriser 4.3gen + apha 1 gen 2

 

[ktbarrentine]

See if this pdf attachment comes through. Is this the piece you are referring to? ​

(if the attachment is not clear, do a google search for mercruiser service bulletin 91-25)