Henry, The Yamaha 4hp is a 4 stroke, so, vastly different from your Mariner. My 1976 M17 came off Lake Superior and had a Honda BF100 10hp 4 stroke on her! Talk about overkill. I purchased a new Yamaha 4hp 20" model in 2001. It is a wonderful outboard and fit the M17 perfectly. I did use an motor mount to get the engine completely out of the water while sailing. I imagine that outboard comes up for sale on the used market occasionally. Before the Yamaha I had an older Johnson 6hp 2 stroke, circa 1965 or so. Frustrating little devil. It worked, but had this nasty habit of killing and not restarting at the most inopportune times, like pulling into a crowded marina. The BF100 Honda I used on my M23 for years, still have it and plan on mounting it on a fishing boat I'll be restoring. Mr. Bones Mpls ____________________________________________________________ Sponsored by https://www.newser.com/?utm_source=part&utm_medium=uol&utm_campaign=rss_tagl... People Are Furious With NBC Over Trump Town Hall http://thirdpartyoffers.juno.com/TGL3141/5f88477db8132477d5049st03vuc1 Dr. Fauci Broaches the Subject on Everyone's Mind http://thirdpartyoffers.juno.com/TGL3141/5f88477dd73bf477d5049st03vuc2 Cops: Girl, 8, Died After Being Forced to Jump on Trampoline http://thirdpartyoffers.juno.com/TGL3141/5f88477e2cdc477d5049st03vuc3