I have a 05 johnson 50. The lower unit is gone, do not have one. It appears I need to find between a 89 -2005 40, 48, or 50 lower unit to replace this. I called a johnson dealer and he though that an older 90 hp would fit but that the gear ratio would be different but that we could probably even things up with the prop pitch. Does any one agree with this, heard or this, is this a bad idea? I just have no experience with this, if this is just jury rig fix I would like to know thank you.