Alright here goes,
I measured multiple radiator supports and can now confirm that the 26in radiator support for the 69 to 73 c-bodies all have the same mount point dimensions on a single plane. They are however not square, the drivers top bolt hole is in perfect alignment vertically with the bottom hole on that side and the two top holes driver and passenger are horizontal. It is the bottom passenger hole that is higher on the frame and set toward the drivers side a little. I have loaded the pics below and these are the dimensions in Millimeters which will be more accurate.
Top bolt holes horizontal -- 716mm apart
Drivers side bottom hole is 360mm down from the top hole and is at a perfect 90 degrees from the horizontal.
Passengers side bottom hole is 296mm from the top hole.
Bottom holes are 707mm apart.
I also am 99% sure that the 66 to 68 radiator supports for Cbody will be the same dimensions.
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