This had me scratching my head and cussing JD the entire time until I found the procedure in the Tech Manual. It was easier than I thought once you know how. I found you video after the fact :) I may drill and tap two more bolt holes in that channel to help retain that cover nice and tight.

We have cut that whole box of with cutting wheels and reciprocating saw in order to get access to the back of where the clips go. Then welded nuts on to the back. Welded the box back on. Painted and hopefully good for ever. Unbelievable that JD would use a cheap clip system there. I would have gone with replacement clips though if the parts guy had mentioned them. Good video, thanks.