Don't know if this will give any insight to the roof rail "spot welds" questions, but here goes. As a former Ford Motor company Body shop employee building F-Series truck, one of my jobs as an off-buck welder (one that manhandled the heavy ass spot guns for shotting many welds in various panel locations) I was fortunate enough to be one to actually weld the roof to the drip rails. This bohemoth's welding tip was not of round type tip as was the rest of the spot welders, but instead, was a narrow and long tip approximately 1/8 inch wide by 5/8 long blade type using approximately 60 psi and a weld time of .83 seconds. to pinch and weld the drip rail. Now, across the windshield and backglass, well that is pretty self explanatory. Hope this will help answer some questions.