Mark,
I see what you're talking about, but the cover would be mounted to the 2 top metal "flanges?" either side of the neutral bus.. & those aren't clean like the locations I think you're referring to... If I remember right, & if I'm looking at this right, this is a GE 3phase (400A?)panel.. Isn't the deadfront attached to the panel cover??

What was bolted up there?? [Linked Image] Looking at this again is making me think something along the lines of a forklift skid.. The blown out section looks about the same size to me...
Tim, I've some across water damaged panels before also, but this is one hella blowout!

-Randy

PS Bob, don't forget to reidentify the white on the top breakers (Ckts 1,3,5 & 2,4,6) [Linked Image]