The standard dual exhaust system had resonators dating back to '67.
When chambered had to be dropped as standard equipment, the interim Z/28 system was the 67-68 deep-tone muffler w/o resonators. SS350 was not part of the recall and was not mentioned. By April, the interim system was dropped and Z/28 received the same production N10 system as the SS350.
Probably the only exhaust system a '69 SS350 had was the standard N10 muffler/resonator system.
