Below is an image of a badly deteriorated
inner fender panel. The three mounting holes are 1/2 inch in
diameter which allows for a degree of freedom with the 1/4
inch bolts used to attach the top frame.
The top two mounting holes are 3 5/8"
from the top edge of the panel. The left hole is 17/8"
from the front edge. These measurements are to the center of
the holes. If you click on the image you will get a slightly
bigger image.