69 Dart/Barracuda 340/383 tail pipe size?

the Accurate Liimited tailpipes are 2 1/4 unless you ask for something else.

IMHO if you want something smaller it would be more straight forward to just stuff a rag up the tailpipe

Not all of us are into this for hot rodding, stock works just fine. I have plenty of other Darts for hot rodding. I don't know how anyone owns just one A-body...