4. ...while the inboard flange of the framerail is plug-welded. Though difficult to see here, at the forward portion of the trunk pan assembly, where it kicks up over the rear axlehousing, there are two layers of panels where it connects with the framerail, forming a boxlike structure. The floors come assembled with the shock mounts already built in, leaving no access for the spot welder; the only option is to plug weld. The spot welder will weld multiple layers, but they have to be laid one on top of the other.