When towing heavy loads especially off road the frame can bend at the hole just in front of the axle. 
While this was designed by GM to allow the frame buckle during a rear end crash it is seen as a weak point when actually using your vehicle as a "truck". 
Off road tested and proven strengthening of your frame. 
Weld on steel plate will ensure the strength you need to use your truck worry free. Install is straight forward and should only take an hour or two to weld on. 
Consult a qualified welder to perform the install to gaurantee maximum strength.
1 kit comes with 2 plates sufficent to brace both frame rails. 1 kit = 1 truck
These are laser cut and sent directly to you.  Takes about a week or two to get to you. 
Here is an install video of these plates. https://youtu.be/gAiIiPnwqd0