Does anyone know the size and dimensions of the rear sub frame exhaust hanger?
Thanks,
Mike

It is about 4" long rectangular with a couple of little notches. Your 69 convert has heavier frame rails so you won't find them back there. 69 coupes with dual exhaust will have them.

-Mark.

I measured an original Z/28 to make mine. It was 4-3/4x2x1/8. There is a semicircular notch about 1/2" diameter at the midpoint of the top and bottom edges. ie center of the notch is 2-3/8" from the left edge.