I have a 1971 Dart Swinger with a /6 that needs a new muffler. The previous owner used a universal fit type. I'm trying to find out what I need to do the job correct. Could someone tell me what the correct inlet Dia and location is and what the correct outlet dia and location is ?

You need to take into consideration what ever head pipe and tail pipe the car currently has on it... aside from what was OE correct, with a replaced exhaust system (obviously assuming so after 45 years) the rest of the system could be anything sort of.

If you are talking about replacing the entire system with an OE correct system, perhaps check with some of the exhaust vendors out there ? (not sure how many would deal in slant stuff though)

Walker exhaust would be likely to have the system from front to back. You could measure the pipe going into the muffler for the correct inlet size. You should be able to figure out whether you need a center or offset inlet and outlet by looking at the area the muffler goes in. Same with the tailpipe location. You can get walker stuff at the local parts stores.

Try Rock Auto. They have all kinds of Slant stuff.

flat, tom over at www.accurateltd.com has everything you need for 6 cyl exhaust. thumbs up. ronnie

what Oz said, unless you want OE correct (& I'm thinking that ain't the case) I'd just get a parts house muff of the same dimentions as what is in their now (that'd be the cheapest) & call it good. & /6's dont require much muffling to keep em quiet