62 gards have brackets spot welded in the park light section that you'll have to remove if you want the round lights. Found this out the hard way fitting a 60 gard on my 62. Had to drill out welds and transfer them over.
the grilles them self are different shapes.
as mudnguts said, the 62s have little tabs that need to be cut off to fit the round headlight surrounds. (having said that NOT all 62s had the square lights, my first 62 had round headlights)
here is a pic of the two grills, i can take more pics of both guards headlight surrounds etc etc, if you need me to, just let me know.