This is the step that the factory skipped over, and the reason why most welded flange bonnets are LONG GONE… We apply weld-thru primer to the flanges and the skin. Most 1961 bonnets rust through the outer skin badly along the flange lines as rust builds up between the flange and skin. When I was a kid, NOBODY wanted the welded bonnets, not even people who should have had it on their car – they were all pretty much wiped out with bad rust. What was really great about this panel was that it had the welded louvers, but had never had welded flanges – weird! I figure it was either a replacement panel from Jaguar from the early days, or, more likely, just happened to be from a transitional car right at the point where they were switching over to the bonded flanges. Interestingly, the rear LH mudshield flange WAS spot-welded to the louver edge, but bonded the rest of the way…