What is Gear Case 25 vs Gear Case 35 (1980 25HP J25TECSA)

I have a 1980 25HP Outboard. The impeller is bad and needs replacing so I decided to save some money and do it myself. The model number is J25TECSA. When I search for the parts, though, every website asks me to choose between "Gear Case - 25" and "Gear Case - 35" before making my part selection. The only problem, for me, is that I do not know the difference between these two nor which I have.

For reference, I also see the option for Exhaust Housing 25 and Exhaust housing 35.

research has also revealed that there is a 3 bolt variety and a 4 bolt variety of water pump housings. Is there a way I can tell which mine requires before taking it apart?

Any thoughts and/or feedback is appreciated.

??-------If you have a 25 hp motor you look up the parts for the 25 model.

racerone said:

??-------If you have a 25 hp motor you look up the parts for the 25 model.

Click to expand...

So I first thought the same thing... but then I began to wonder why they would give "Gear Case 35" as an option when I am searching by my specific model number... why would it not just stick to the 25 parts?

That is how the parts manuals were printed !!

35hp has the thru hub prop with solid gearcase and the 25hp has non thru hub with the split gearcase. They are not interchangeable as the leg is different also. The powerhead is interchangeable.