Originally Posted by Furno68C20 (Post 9170863)

I’m currently swapping a 292 in place of a 250. 68 Truck originally had a 250. The 292 I have has a 3” 3 bolt triangular exhaust manifold flange. This causing a problem since the truck has a 2” 2 bolt flange.

From the research I’ve done I should be able to use a 250 exhaust man that will fit a 292 head and then mate to the OEM exhaust.

Did the 292 come with different exhaust manifolds based on what size the truck was? C10/2030 - 2” manifolds: c50/60 3” manifolds?
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Originally Posted by Wrenchbender Ret (Post 9170935)

You are exactly right. The larger manifold came on the larger trucks. 1 1/2 tons & up. The 250 manifold will fit the 292 engine but the larger manifold is better. The small manifold is restrictive on a 292 engine. It causes warpage & cracks in the smaller manifolds.
You will need to fab an exhaust pipe extension or have a muffler shop make it up.

There’s always some modification to do. There is a break in the exhaust pipe under the driver door. I’ll bring that piece along with the manifold to have fab up.

Thanks for the info here.

George