Chrysler Aluminum Manifold 4100337

Watching.
I can honestly say that I have never seen or heard of one of those before.
The only factory aluminum LA manifold I know of is the six pack.
Well, okay, there were LD340s that carried a factory part number to make them NHRA legal- but strictly over the counter, not assembly line stuff.
This ain't either one.
Any other markings, Pentastars, casting dates?