Headers were placed on my roadrunner years ago.
Iím replacing with stock exhaust and need to know the flange size that buts up against our stock manifolds.

Note:
Engine is a original Supercoupe 360 with original manifolds attached.

Built in donut is causing me to have a hard time measuring since itís not a flat surface.
But the two holes appear to be 4in apart at centers with a rape measure.
Also the engine is now in the car and itís not easy getting a tape measurement on it.

I need to call the muffler shop so they can order me the correct size before I show up with the car on a trailer.

Thanks, Lee