I seen them on e-bay
They sold or are selling for a pretty good buck.
Do you have a place around you like an older marina that would have some older boat around ?
They might sell you one.
That would be the Electramatic Shift control. There is a $400 switch in there.
Be certain that you get an Electramatic Shift control and not a Hydro-Electric shift control. They look alike, and if you use the wrong one it will seriously damage the motor the first time you try to put it in reverse.