Muffler Part Number id?

"It is about 25" long, has 2" exhaust pipe openings"

http://seattle.craigslist.org/est/pts/494353156.html

Im not usualy anal about NOS stuff but it is right down the hill from me and my 73 dart 4 door with a 225 is so tits on original it hurts. I wouldn't mind getting a NOS muffler for it cause I was quoted 74 to have one built.