There are a few cam frofiles in the crate motor line up that are shared with the mercruiser mag andstd and eve nl the l29 Vortec motor .specs are different from merc book to gmpp cataog but same cam .(s) and freeze plugs .and head gaskets . The gotcha is in the vac advance hei dist and oil bypass plug pressure specs .seems the ones slated for marine use have a little better q.c.