I used to have a Leer shell and it cracked my bed in two places, I welded up the cracks and it did it again - twice! I have since sold my shell and this last time I made two small 1" by 9" pieces of sheetmetal from an old door, bent and formed them to the cracking areas and welded over the problem areas. So I will have to see how this works, once I get a spray in liner, it should help aswell.
Sorry I don't have any cracking pics, but these were the problem areas