I have a 1991 Mariner 3 Cyl. 50 HP motor I bought used. I removed the lower unit to install a new water pump kit and changed the lower unit oil. My question is what is the correct way to re install the lower unit? I am not sure what to do about the shift shaft. I can rotate the shaft and get it into nuetral. Do I then put the lower unit on with the shift linkage on the engine placed in the center of its forward and reverse travel? Any help would be appreciated.