head casting number 4772576?

340Dart,
It was due to the tall short turn and the shrouding in the bowl, but I wanted to see what they would do out of the box and to me they were much better than expected. Most heads that flow well in the lower lifts will almost always lose flow in high lifts, and this is common to factory casted heads. This is why the need to do bowl blending and gasket matching work.

BoredandStroked,
These heads were never put on any production engine, but they were offered as a stock replacement, for the T/A and standard heads, then they added the over sized holes for the non magnum engines. So they made them fit 3 different applications in one casting, trying to save cost I guess.