I now see your Serial number starts with a 0 not an O, making everything dbkski said correct.

And no the L29 is a gen 6 block, basically what the 7.4mpi from 96-2001ish is. Your engine is more than likely close to an L19. That service manual link you posted is not for you.

You can get your service manual from mercury's parts catalog https://www.mercurymarine.com/en/us/.../parts-catalog
Just type in your serial number correctly.