I think there were originally several different exhaust "elbows" available. The downflow type with the integral raw water injection port (shown in #4 above) seems to be the most common. It has the oft noted disadvantages of possibly allowing water into the exhaust manifold and needing periodic replacement because of hot saltwater eating it up.
A second type of exhaust fitting is shown in my Lehman parts manual. It is a straight threaded fitting used for connecting metal exhaust pipe instead of the exhaust hose fitting above. That is the fitting I have and seems to be similar to OP's. Mine is female threaded and the original owner threaded 3" stainless pipe into the fitting and fabricated a custom high-rise exhaust pipe with the raw water injected well down stream. It is on the backside of the exhaust pipe in the picture, where the SS pipe is no longer discolored from heat (lagging removed). No possibility of raw water entering the engine by over-cranking (without starting) for several minutes.
As a bonus, the heat and salt that eats the insides of cast iron elbows doesn't happen. I recently pulled and examined my +40 year old exhaust fitting and it was fine on the inside. All the rust pitting was on the outside of the cast iron, so it got a new coat of high heat paint. Should be good for another 40 years.
