BE AWARE that this mount kit will reduce your truck bed width. In 2016 UWS truck boxes reduced their belly widths by 2" and these reduced belly widths will fit with this kit. For example, a 69" box before was 61" and the new models are 59". I have a near new UWS truck box with the 61" width, so instead of buying a new box I just ended up putting one of the standard mounting brackets on the very front of the front Trac Rac and pushed the tool box up to that bracket. I then drilled through the tool box, Trac Rac and bed rail at the front and from this kit just used the 2 pieces that are short 1-1/2" profiles of the Trac Rac and drilled there as well. By not using this kits brackets I was able to reduce the box height that extra 1/2", no big deal, but the only positive I could come away with. Buy the Trac Rac ladder racks first and if your box will not fit your truck with Trac Rac brackets, don't buy this kit. Find yourself something to match the Trac Rac base height to shim up the rear end of your box and save some money or just cut off 2 inches of the Trac Rac base.ALSO, the parts in the picture on the product page are not what I got.On a side note, Trac Rac should be making their racks long enough on the front end to not need this extension kit and come standard with the mounts pre-drilled for truck boxes, but then they wouldn't be nailing you for the extra $60.The premise is good, they really should warn you about the added width the brackets add. Make sure your toolbox has enough clearance between the bed rails to fit after adding the brackets. It was a problem on my 2005 GMC sierra, I actually modified the toolbox.This adapter kit fit my existing tool box. I was able to then install the TracRac ladder racks on my S-10.PERFECTI agree with the previous review. A drill and tap combined with some screws and washers with a piece of wood to support the back end of the toolbox makes this happen for about $5 worth of hardware. If you need to buy a drill bit and tap then add a few more dollars but at least you have some tools at the end of the deal. I also made it a lesson for teaching my son how easy it is to just do things for yourself.This is nothing more than the out of the box clamp with a tapped hole in the top.Save yourself some considerable change by simply drilling and tapping a hole into the base.Even if you need to buy drills and a tap, it's cheaper and you get some tools out of the deal.Some have mentioned holding up the weight at the rear of the box. I simply cut 2" off the rear rail and mounted it under the rear edge of the toolbox. A grand 30 minute project!