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.