Maybe I can answer this first question. "I don't know how all these experts come up with some of this stuff??" Research, documentation and original low mileage examples. Parts books and actual tech/service manuals show (2) part numbers (left and right) for the head pipes. If equipped with an h-pipe there would have been (1) part number as with the hemi cars. When designing our 71 440 B exhaust systems we used a 16K mile 6 Barrel RR that we had access to locally. Also factory specification information was referenced as the base line for our production pipes which does call for a right and left exhaust pipe. We also manufacture an h-pipe for those that would like one but it may not be correct according to some. If you read the following attachment it explains some of what is said above. Individuals have claimed that some Canadian cars did have h-pipes installed but so far this cannot be substantiated by actual documentation. If anyone can add further documentation to the subject it would be great. As it has been said before "never say never with Mopar".