I recently picked up a lower unit for my 1991 90hp Johnson. It came off a late 80's 115. The replacement unit has a fitting on the front outside of the case, up in front of the shifter rod. Let's like an air line would connect to it. What is this? Also, is the shift rod hard to replace, as it is a differnt style than my old one? I plan on swapping out the shift rod from the old unit. Thanks in advance.
