What is the issue that rubber is needed to fix?
Those of us with the Tactical 4x4 rock sliders have experienced some creaking sounds (upon acceleration) coming from the contact between the sliders and the body/frame. Since these sliders are heavy and have a lot of contact with the truck, it is not surprising that there are some normal creaks due to the rubbing and/or articulation.
Tactical 4x4 recommends putting rubber or foam strips where the slider comes in most contact with the body/frame - Umberto was able to do this with success and decreased the creaking. I have only slight creaking - you have to turn off the radio and A/C to hear it, but I am still planning to work on it.
My truck is pretty loud anyway because of the roof rack and the fact that I raised up the compressor, so it's not a big deal, but I will see if I can decrease some of the creaking noise.