the only engines with dual exhaust on the Mach 1 were the 351-4V and the 428CJ-4V. The 351-2V came from the factory with a single exhaust setup and no cutouts (standard valance). Another oddity that most people don't know about is that the standard transmission with the Mach 1 was the 3 speed.....

randy

 

Thanks bossman! I feel much better now.

 

I would guess by the earlier years that 2v and 4V could have single or dual exhaust from the factory. Best to check your car for the original mounting point for either system. That would be IMHO the best evidence either way

 

If it had duals, it will have the nut plates in the frame where the muffler hangers bolted to the floor on both sides (Just in front of the upper shock mounting points). If it was single exhaust, they will only be on the passenger side. My 70 Sportsroof is this way, and I'm trying to figure out how to mount the muffler hanger on the driver's side. I think I am going to use a pair of U-nuts, and put a little slice in the pan next to the mounting hole openings.