Hi Folks,<br /><br />I am looking to swap out my lower unit with a used one. I have a 1979 19 foot EBKO Open Bow Runabout with a 228HP (305 Chev) Merc I/O. The Outdrive Serial # is 5324919. I measured the center to center distance from the top 2 mounting bolts and it is 5 1/16 inches. I would like your help with the following,<br />1. Will all pre 1980 drives work and are they all 1.5 ratio.<br />2. Besides salt water use what would you stay away from in a used drive.<br />Thanks for any help you can provide.<br /><br />Bob Fifty