Thanks Rob! A neighbor of mine has two of these that have never been installed. He said he bought them as new crate motors for his boat. Never did install them. He built stands and they have been sitting for 10-15 years. They both have the 3933163 intake also. Both are painted black. I took one valve cover off and they are definitely unrun motors. Flywheels were on them as well. Why are the heads and block #'s that far apart on a crate motor? Could these be simply 2 engines built to ls6 specs? Is that in the norm? What is the value of these engines? Thanks. dave