Originally Posted by broncobowsher
Ford has always had a thing for cast in manifolds, remember the old Falcon six?
That's the first thing I thought of when I saw it, but IIRC those were intake manifolds.
Chevrolet flirted with this for at least a while in the 70's. My Dad had a mid-1970's Nova with a 250 inline 6 with a cast-in intake. The heads on these engines were notorious for cracking. He wound up swapping to a later engine with a separate intake at some point.