Need a serial number for your engine to make sure it's actually an 89. 89 was the first year for Merc manual 15. But 89 boats quite often have 88 or 87 engine packages.
You should find a metal tag just aft and above the starter.
right now iam home and i caunt find my little note book with my boat info.
but last year i post the engine serial# and you stated it is indeed a 1989 engine so iam pretty much shure. i thanks dons in thursday i will post the serial# thanks.