Holley 3 barrel carb 3916 950 cfm

They were also used on NASCAR engines a good bit back in the day. I sold mine a while back. If you look at older intake manifolds like the LD4B, LD340 and DP4B you'll see a notch at the rear of the center divider. Contrary to the "siphoning" theories behind this notch, it was completely physical for being there. It was there so the rear barrel of those old carburetors could open. No other reason whatsoever.