difference between 450r and 400ex arms?

[extremeisaac]

Is there a difference in the width of the stock 450r a arms and the 400ex a arms? If so, are they interchangable between each other?

[Pappy]

The 450r arms are wider at the frame mounting positions, and they arent interchangable.

[extremeisaac]

OK thanks.. looking for a budget way to widen my wifes front end