Ok somebody explain to me what the difference between a 502/450 HO gm crate motor and a 502/450 gm crate marine motor other than the slight cam difference,brass freeze plugs,and a 8.1 oil pan versus the 6.0 on the HO. If you look at the specs in the gm performance catalog they are nearly identical. They HO even has the composite head gaskets w/stainless fire rings and brass freeze plugs . I'm more less talking the rotating assemblies and blocks. The consensus I'm getting is like 50/50 some say they are built with different tolerences and some say no difference. Somebody fill me in please. This seems to be a huge mystery in the marine world.