There are seven bolts inside the fender tub that hold it to the side of the bed. Get those, and the carriage bolts thru the bed wood out, and the tubs will lift out of place. The bed sides, and front panel have flanges that the wood rests on top of, not below, and is bolted thru. So there's really no way to install the wood from underneath(that I am aware of) Start in the front corners, and work your way toward the middle plank. Dont drill holes or bolt anything up till you have everything in place and adjusted properly. When re installing the fender tubs (last) position the seven side bolts first, then line up the bolts that go thru the wood, then tighten it all down. Thats how I've done it. Some others may have some tips/tricks as well. HTH