Assuming your asking about Mach 1's. I'm not positive but I believe all 2 barrel C or W were single exhaust. They also did not have cutouts for duals in the rear valance, the tail pipe turned down at the end. Refer to Coolfords.com for 1970 Mach 1 specs. If you add the duals to the 70 they also had a special 70 only chrome or stainless tip.