Abstract: This is an apparatus to facilitate securing radiator tanks onto header plates of automotive radiators and the like of a type made either from brass or of plastic having a gasket trough and integral header tabs. It includes opposed rails suspended from an overhead support, preferably circular to afford 360.degree. rotation, and arranged for individual movement towards and away from each other in substantially parallel relationship to support the header on different thicknesses of radiators for mounting the tank thereon. In one position, opposed edges of the rails are notched to hold radiators of varying sizes and types with easy access to header tabs on plastic radiators and in an inverted position, the rails are provided with a flange to support the underside of the gasket trough on plastic tanks with good access to the tabs.