That is a Gale 5D10 motor.  Gearcase/water pump are the same as 5hp Johnson TN-xx models, except for a couple of items.  Drain gear oil, or you will wind up with oily shoes, then cable has to be disconnected at the neutral lever, then gearcase and 1/4″ plate (#17) with the water pump can be dropped down to access the pump.  Cable will follow it.  No fear, the cable is fed up through a (#5) pipe to re-install.  Warning!!  If cable end is frayed, a different procedure is required.  Don’t pull a frayed cable down or you’ll never get it back up through the pipe.

Hint— a 5.5/7.5 HP Johnson impeller will work by reaming out the center hub to fit over the slightly larger drive shaft.

I have a Gale version and the Sea King. Both 5hp. One has neutral shift and one doesn’t. There’s a couple years difference in them though.