It sounds like you have the OMC Stringer system which predates the Cobra that I have and have done just about all the maintenance on...
So I don't know Stringers....but there are those who do..
Go on to the OMC forum on
www.iboats.comPost up your question... A member by the name of Boomyal knows a LOT about these drives.
Just to be sure, this is the one with the big boot around the transom and does not have trim cylinders like a Merc or Volvo SX right? Probably a 1985 or older boat cause the Cobras came out in 1986.