Conversion to longshaft

I have a 40hp Mariner (40M) which is 15" from transom clamp to cavitation plate.Can I convert it to 20" to fit my boat?

Sure. All you need is a long shaft motor, and they are more common.

Jeff

If you don't like Jeff's idea there are a couple after market places that will provide you with the spacer (for the leg) plus a new driveshaft and water tube for about $750 bucks (last time I checked prices).

Of course you have to tear down the lower unit to remove the pinion gear to change out the driveshaft.

And since it often requires shims to get the pinion to mesh properly with the drive gears, you at least need a shop to shim it for you or you could toast your gears after a re-install - and since you got it all torn down you may as well reseal it while you are at it (80-100 bucks for the kit plus labour).

So you could be looking at 1000 bucks plus a few hours labour - say $1500 if you are lucky - which is about 200-300 bucks more than I would pay for a "running well" mid 1980's 40 horse long shaft on the "used market".....

I think he's liking my idea better and better!

Jeff