The speedo hose starts first in the drive
When on the trailer and in travel position you should be able to reach in anc plug it in the other drive. Mine has a yellow plug that clips in. Then you will have to reroute the hose from the inside of the boat. There is a little hose barb on the inside transom mounting. It should be directly above the shaft. My port side is unplugged at the drive and capped at on the inside.
I got tired of blowing off my hose at the speedo in the dash at anyhing above 80
Always had to reach into the engine bay to unhook the hose. To lazy to get in the water.
Or you can do what I want to do and buy a GPS for the dash.