Abstract: An installation support of a loading floor of a passenger car is distinguished in that it is a component which is different from the bodyshell of the passenger car and is provided in order to define fitting positions of side wall panels and of the loading floor relative to one another. Furthermore, a welded assemblage of a passenger car body has at least one rear longitudinal member. The welded assemblage is provided in order to be screwed to such an installation support by a screw connection. The screw connection has cage nuts which are provided for the screw connection and are guided moveably in the longitudinal member transversely with respect to the longitudinal direction of the longitudinal member.