Looking for some help. Does anyone know if the 3xxx motors (GenIII) exhaust manifolds will fit on the 3.1 GenII heads. The GenIII mani's look like they would flow much better than the stock GenII manifolds. I think the GenIII heads have "D" shaped exhaust ports, vice the "O" round ones on the GenII, but again, from pictures they look like they will fit.
Thanks in advance.
edit - Well they fit. I got a pair of front manifolds off a Malibu 3500 motor and they fit on the 3.1L heads just fine. Yes, they are "D" shaped and the heads are "O" shaped, but there is enough material on the heads for a slight porting on the edge. They didn't require any slotting, or grinding, they just bolted on.
[This message has been edited by qwikgta (edited 09-15-2020).]