What he said, it's pretty common for all ford's. I had to do the same thing to my '03 F150. Dremeled the bottom lip flush, and then cut maybe a 1/4" into the top. Don't touch the sides though. And use flush mount screws to attach the plastic clips to the F Series.
EDIT: It looks like you got it.
I just bought one of the F700's for my 04 F250 SuperDuty. Will I have to do this customization to make it fit? Does anyone have any pics showing the work required?
Thanks,
Steve