5.7 Hemi Crate engine Oil Cap

I have a 5.7 mopar hemi with a carburator. I am missing the oil fill cap that screws onto the intake manifold(4510581). Anyone know the size/threads?? Where can I get one? It does not appear to be AN or a standard inch size.

Do you have the 5.7 Mopar Performance single plane intake? I take it you do. Mine came the same way. I went through Henson Motor's to get my oil fill cap. 866-753-6152 and ask for Art in the parts department. He'll hook you up.