Nice catch, Sean!
Due to a 1/4" mis-measurement, I can't put my big 13,000 lb shackles on there so I down sized to a 9,000 lb shackle that fits fine. If I wanted to get the big boys on, I'd either have to grind the shackle mount holes out a bit or cut some clearance holes in the skin next to the shackle mounts. Holes in the skin would be ugly but wouldn't weaken it because the shackle mounts go all the way back and are bolted to the frame. Grinding the shackle mount holes out a bit would work fine because I left plenty of meat out there but it would take forever with the die grinder. In the end, I figured the 9,000 lb shackles would be fine .
What do you think?