Ding Ding,
Is this how your boxes started life..[or, something like!] http://jbl43.com/?pid=94861707 ?
Shows no 'trim' at the front - flat front edges.
As against http://blog.kenricksound.com/2015/09/jbl4343bwx_8.html
Shows those edges looking "very close" to what you have...!
In my packing to move.. I just can't quite lay my hands on all my drawings and measurements...
DB