Hi folks, just a quick question, I am trying to find a lower unit for my 1989 mercury 4 cyl. It has a jet on it now. The transom to top of jet unit is 18 inches and the jet unit is about 11 inches. I suspect this is a long shaft, but am having a hard time confirming such that I can confidently track down the unit on sites like ebay... thanks in advance for the advice