I put a Gardner on ours and love it...nice rumble at idle but quiet on the highway...but you can do very well at a local muffler shop that does custom exhaust for half the price.

The factory configuration is a pair of smallish resonators under the floorboards, and a larger dual transverse crossflow muffler between the rear axle and gas tank, with two tailpipes exiting between the rear springs and quarter panels behind the rear wheels.

350 2bbl had single exhaust.