Re: 1962, MERC--9.8 hp. Impeller change- so where is the pee hole?
I don't know when Merc introduced the pee stream to ensure that your water pump was pumping water up to the powerhead.
The hose barb that feeds it is about 1/8" pipe thread to about 1/8" hose. The pickup is usually either off the exhaust manifold water jacket or the water jacket that covers the tops of the pistons.....on V higher hp engines it can come out the top of the block if not plumbed off the tstats.
The outlet is usually on the Starboard rear of the engine, in the lower cowling and angled down at about 45 degrees, so that the operator of the engine can see it as they usually sit on the starboard side of the boat (nowadays).
HTH,
Mark