First 1967 383 installed in a Barracuda

383 blocks are not all the same. In the Barracuda (and assume Dart) the motor mount uses the forward mount position on the driver's side to clear the steering box. Not all 383 blocks have the needed forward bolt locations cast or threaded into it. I have seen these castings on earlier '60's engines. When installed in a 'A' body, then the rear most "standard" motor mount ear is cut off. Hence a 383 in an 'A' body uses only the forward motor mount ear and bolt holes in the front of the block. The exhaust manifolds are not 'inferior' but rather necessary to wrap around the steering column but causing a power loss. The factory is not obligated to provide header clearance.