I'm trying to replace the muffler on my 1971 Dart swinger /6. Could someone tell me the inlet Dia and the location and the outlet dia and location ? When the previous owner replaced it they used a universal fit. I would like to put the correct one on

What do you mean by "correct"? If you mean exactly identical to original equipment, that's no longer easily possible; all the exact-direct-fit mufflers have been discontinued for many years. You could probably find a new old stock item at Old Car Parts Northwest, but what is your goal? The original mufflers on these cars were much too small, because the car was cheaper to build that way. There is a lot to be gained by making a muffler selection more thoughtful than "just like original".

But if you're bound and determined to put on a muffler as close as possible to the original, it's this one

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