No, it is the same. Only difference found is that the dipstick hole was plugged because in th boat application the dipstick goes to the bottom of the pan and becomes a suction tube to withdraw oil. I just drilled out the boss that was there and inserted a regular dipstick tube. As Bob mentioned, some were counterrotating, but now they just do that in the lower unit (run one in reverse).

One thing to watch for is internal corrosion, especially if the engine was run in salt water. I spent a good amount of time with an air hose, shop vac, and water pressure cleaning scale from the water passages of mine, and this was after it was hot tanked at the machine shop.

Otherwise, every part has a GM part number stamped on it, and I was able to use regular bearings, gaskets, etc from a Chevy truck application.

Even when I worked at a Marina, we were never able to determine if the parts like pistons, rods, etc were any different from passenger car parts. Mercruiser and Volvo guard this info like the National Treasure, and would never fess up. However, it seems like these are just passenger car blocks that get brass freeze plugs and head gaskets, and maybe a different cam profile, and are sold to various marinizers.


Hope this helps,


Don