So, 2003 Honda 90's
There is no shift linkage to disconnect. on this motor. You don't have to remove the trim tab to access the 5th bolt(nut in this case).
There are 5 -14mm nuts and washers that need to be removed.
The lower part with the impeller housing is then separated.
This was a bit of a fight, although it just took some time. The longest bolt that the lower slips off of, is at the back near the trim tab, and it had developed a close relationship with the lower unit. It required some patience and some work, and some penetrating oil, as well as a judicious application of a dead blow hammer and wide thin paint scraper to get it started, and it did it's best to resist all the way.
This is aluminum, so don't use a screwdriver to pry with. The heavy duty paint scraper I used, had a 5 inch wide blade, was thin, and worked great.
I intend to use some anti seize, on the studs when I put this back together, to prevent a repeat of this close association.
..but I won.
The other 4 bolts didn't offer any resistance, but they were about 1/4 the length of the one at the back.
When it comes loose, it is simply pulled straight out. The drive shaft is about 30 inches long, so it needs room to get it out. The shifter, is just a rod sticking up with teeth on the end, as is shown in the link above provided by "shellndanm" for the later model 90's.
The rest is pretty straight forward.
4 bolts are removed that hold the housing around the impeller. It is worked loose, and lifted up off the shaft(There is an Oring under the housing that gets replaced, that seals to the plate under the impeller)
Then the impeller.
Then the key is removed(It just sits in a flat spot on the shaft. The impeller can only go on one way).
Then a plate below the impeller, and there is a gasket under that, that gets replaced, and was in the kit.
There was a second gasket that is below a plate under the first gasket that was not in the kit, that I had to go and get. Apparently, this one isn't supposed to need replaced, but it was the first one to let go when I was working my way down.
Assembly is in reverse order, using grease where the manuals says to. Use the proper torque where recommended in the manual.
The impeller I removed was not damaged, but its fins/blades, are permanently in a nice neat curl, were they won't push water any more.
The housing looked good, with no wear marks that would cause problems, but they do sell a kit, that includes the housing as well.