I purchased a 1982 Mercury 50HP with a lower unit that was either frozen or got caught on something and ripped out. I ordered what I thought was a direct replacement, but it is slightly different. I don't have the serial number from the replacement lower unit, but the guy said it was from a 1975. The 75 appears that it will fit the 82, but the speedo fitting and hose is missing on the 75 lower unit. No big deal there since I don't have a speedo on the 82 Lund boat. But the 75 has a hole in the lower unit that I am thinking is a drain or pitot type hole. Will this hole cause a problem in the upper unit? The CAM, REVERSE LOCKING part numbers appear to be the same, the splines are the same and everything else appears to be close. There is a flush plug on the 75 that is missing on the 82 but that is no big deal. Am I ok to bolt them together or is there a potential issue.
