Re: 79 evinrude 25 hp
not sure on shaft length but I hope this helps.
89 = 303142 = Pinion Control Throttle
92 = 387057 = Gear and Shaft Short
107 = 388657 = Gear and Shaft Long
http://epc.brp.com/default.aspx?brands=ej&lang=E
Go to "Evinrude" then "1979" then "25904R 1979" then
"Exhaust Housing -25" or "Cylinder and Crankcase" (Depends on what parts your looking at)
Not sure even if this is the right model.
Also to get these parts out which look very similar to my engine, you are going to have to remove the Control Lever and pin (Listed under Cylinder and Crankcase as Part number 37)which is the long rod that fits down into the Pinion Control Gear and goes up the side of the motor. It is attached by a spring (Listed under Cylinder and Crankcase as Part number 81) to the armature under the flywheel around where the plug wires come out, and also by two flat head screws that hold it to the side of the engine. It should just pull up and out after disconnecting it. Be carefull though not to flex the end that is attached under the flywheel as this end that is attached by the big loopy spring can break off very easily. This is what I broke the other day.