Projects GMC intake?

Ok guys, I got this 2x1 manifold in a box of stuff with a 270 GMC. It doesn't fit the jimmy, it's too long. It's 19 1/2" center to center end ports. "Chapman" cast into it. It's super light. ???

 

Bump

 

Yes, I have searched and can't find ANY mention of this manufacturer, i thought possibly IH but attachment lugs are clocked wrong on the pictures I found. Anybody ?

 

Carb flanges look like for Winfields. Could be mag for some exotic early racing engine.

 

Thanks Andy, in the box was one cast adapter from the square flange to a 2-bolt Zenith looking flange. It's at the shop right now, I'll get a picture of it tomorrow.

 

Ok bringing it around again, It is aluminum. I have searched everywhere and talked to old mechanics and have found Z,Z,Nada. Chapman is big with Lotus but that's all I can find.

 

Ok, might have it figgered out- originally I looked at a pic of a 361, 426 ,505 Jimmy but Now I believe it was maybe reversed. I recently found a pic of an Ellis 2x1 and the lugs appear to be correct on it. Does anyone have any other info or pics of those big GMC's ? Thanks