4-Door with 340 from the factory?

19DART66 said
Jim Lusk, You are right the W2 head was on the drawing board for the 78 Little Red Truck and was nixed for smog. My guess is that the W2 head does not have the exhaust heat crossover. Which would have made the EGR valve on the intake manifold inoperable which was a part of the smog equipment for those years. Just my guess.
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That makes sense on the smog part. They may have tried other things to compensate. They could have gone to exhaust heat tubes like the hemi had with a special intake, but that would have increased the cost.