An apparatus for welding motor vehicle body component subassemblies at a weld station. First and second pallets are arranged for reciprocal movement between a load/unload station and the weld station and the pallets are alternately moved from a load/unload station to the weld station while the other pallet is moved from the weld station to a load/unload station. Each pallet has a plurality of substations for receipt of component subassemblies and, while each pallet is at the load/unload station, the component subassembly at each substation is moved to the next successive substation and a further component is added to the moved component.