Guys I have the bolts loosened except 2 in the back those 4 are a pain! I can't deep a deep well 3/4 socket and my 1/2 rachet in between the rails and a shallow 3/4 and a 3//8 rachet bottom out.
Only way i broke one loose was with a 3/4 box in wrench.
anyway decided to snap a couple pictures showing how I assume the dealer put the bed bolts in wrong when it was re-painted under GM recall. If you look that short bolt where I think a long should be even has a non shoulder nut on it.
Another reason why you're aways better off doing your own work even techs at a dealership feel it's not theirs and who cares as long as the bed is bolted down I guess…but it made it a pain to break that short one loose in that spot.
left side 2nd bolt back

right side 2nd bolt back. One thing I will say is odd is in the above picture you can see where the nut shoulder has been on this short one where the bolt should be but its not I don't see any markings of a nut ever being there. Maybe the factory messed up and the techs at the dealership just put it back like they found it. Thats far fetched but possibly...