Here's a picture of original 340 exhaust like the ones on my car: http://www.dragtimes.com/parts/MOPAR-CUDA-CHALLENGER-DUSTER-340-EXHAUST-MANIFOLD-SET_330552856424.html
I'm the original owner of my '72 340 Duster and those don't look like the ones that came on my car. The passenger side is definitely not at all like mine.