The 292 never used the intregal head. The manifolds are the same on the 250 & 292 light duty (30 series & smaller). The large trucks used an ex. manifold with a larger outlet.
Like Joe says the 250 carb is smaller bore but now most 292 have had the carb replaced with a 250 carb. The exhaust system was the weak spot on 292,s. If used for heavy duty work they will burn out pipes & crack/warp manifolds. If I was going to do any hauling I would put headers & dual exhaust on it. That engine is practilly indestructible. We used to drive them with the throttle to the floor for hundreds of miles.
