The only difference with the core support between Heavy Duty and Standard cooling is the width of the radiator saddles at the bottom

 

To clarify a little, two row and three row radiators use the same core support and top plate. Four row radiators use a different core support and top plate, but as Mike points out, the only difference in the core support is the wider lower saddles. These are spot-welded in place and can be swapped. Repros are available.