Mariner 20HP gearbox removal

[Munces23]

I am trying to remove the gearbox on my 20HP 2 stroke Mariner Serial No:OD168719. I want to change the water pump impeller.
Firstly does anyone know the year, I think it's 92/93.
Secondly how do I drop the gear box as the gear linkage seems to be holding it on and I can't see where to release it. There is no inspection hatch anywhere on the leg to undo any coupling, if that's how you do it.

 

[racerone]

You need to look near the carburetor ( port side of the motor )---Easy to disconnect link( no tools almost )-----------If electric start then it is easier to remove it for a look.