D stock runabout

[Vector79]

Is there a way to get a racing gear box mounted to a short shaft downhouse? Usind a Merc 500?

[25XS]

There is always a way... I'm guessing the easiest would be a Yamato 102 or 302 gearcase mounted to an adapter plate that in turn bolts up to the stock/fishing tower housing of the Merc500 but I have never heard of anyone putting a legit racing gearcase on a Merc500. Pretty common first step may be to add a nosecone to the stock gearcase that includes a low water pickup point so you can run the propeller nearer to the surface of the water.

In the link below you'll see the parts that make a 15hp Mercury fishing engine ready to accept an OMC 15hp racing gearcase. The Yamato has no waterpump, rather it scoops water from the propeller wash to force feed cooling water into the engine. The adapter plate would need to route that water to a feed hole for the Mercury water tube to do its job.

http://btmco.com/Mercury_AJ_Conversion_Kit.html