Here I am again - about 5 minutes after my previous post - I confirmed what I thought I saw, and that is the two different thread arrangements between the crossover adapter and exhaust manifold. The Chassis manual I just looked at showed it clearly. It also showed that the manifold end (once the crossover adapter is removed) is not a rounded 'ball' end that would fit in a typical exhaust head pipe 'socket'. I also am not looking forward to buying a pipe tap to plug the holes left after removing the butterfly valve shaft.
Instead, I'm going to go find a newer passenger side exhaust manifold that does not have the crossover butterfly valve, but does have the 'ball' formation and two (or three) threaded flanges. It sounds like one heckuva lot less work, and less chance of screwing up while modifying the original manifold.
I answered a previous question regarding exhaust manifold compatability: Headder manufacturers show the same part number for Pontiac 326/389/400/421/428/455 headers, so I am going to conclude that factory cast iron log manifolds are likewise interchangeable (except for round port RA or long branch manifolds).
-Adam (asking too many questions before actually researching!)
|