Abstract: An apparatus for supporting and accurately positioning a massive article, such as a commercial aircraft landing gear, under a second separately supported second article, such as a commercial aircraft, to facilitate attachment of the articles is disclosed. The apparatus includes a main frame having a rectangular floor assembly defined by an array of spaced apart, uniformly distributed ball transfer elements and a border formed by raised end rails and side rails. A rectangular interior frame having a length and width less than that of the floor assembly and having a flat floor plate with raised end rails and side rails thereon is movably supported on the ball transfer elements. A first pair of aligned, oppositely coacting fluid cylinders, each being connected between a different interior frame end rail and a corresponding main frame end rail, operates for selective longitudinal movement of the interior frame between main frame end rails.