I have metal trays of bolts out of kk plant & Dearborn plant with all types of the head markings & I don't thing ford was worried about which brand of bolt went in certain place but more about the size of the washer & the 2 different lengths of those bolts but the assembly line workers were onlyworried about getting cars out the door asap. The 2 upper rad bracket bolts was installed down the line when big block rad or bigger rad for a/c cars or b2s used that upper bracket so those 2 inner bolts could hhave been different than the 2 outer bolts that all cars got when rad support bracket was installed earlier . also on the 69 Shelby fenders installed at aosmith they used that thick sealant under the fiberglass fenders & may have needed the longer bolts. anybody compared the head markings brand verses the length?