Re: 89 johnson GT speedo placement?
Look closely at the forward edge of the lower unit. There may be a small opening that would always be in the water. Further up the lower unit still on the forward edge, you may see another opening OR this opening may be plugged and if so, it will be obvious. That opening would accept a elbow type fitting whereas the top portion of the elbow would accept the speedometer hose.
Unfortunately, the inner passageway of this setup is prone to becoming clogged with debris or salt corrosion, and if this takes place, it is a time consuming project to clean it out.
If a alternative speedometer pickup assembly (available just about anywhere), is to be installed, the installation location is usually about halfway between the engine and the outside lower edge of the boat, OR as instructed on the pickup's instructions.