Lets see about answering some of these questions. First off, this style is made for the replacement of either old beat up rockers or rusted out one's that no longer have any use, or for someone that wants a stronger set up. This is how they are made and installed:
The old rocker is removed and replaced with a new section of 3/16x3x4 box tube with capped ends which is held in place via 6 countersunk 5/16" SS allen head bolts that go through 2 new 1/8" sill plates and are tapped into the new rocker subframe.
Seeing as it's really hard to "slide" across a ladder, the next piece is a heavy duty 3/16" piece of plate the is drilled and countersunk to accept 5 7/16" flat head allen bolts that are also tapped into the side of the rocker subframe.
The under side is attached through a nut strip which is a length of 3/16" plate that has nuts welded to it, flipped upside down and stitch welded to the frame. This not only acts as a mounting surface, but a frame strengthening system as well.
The tube on the side consists on 1 3/4" x .134 wall tube TIG welded to the slider.
This system runs $700 painted and installed with the bars and $600 without.
The next system for those with "California" rockers, or those that just do not need a rocker replacement consist of the same 3/16" slider with exception of the way that it mounts.
The frame mounting is the same. The difference is that this system attaches to the rocker pinch weld with a piece of plate on one side and a piece of 3/16" nut strip angle on the other. The slider is drilled and countersunk to accept 7/16" flat head bolts that attached to the pinch weld.
This system runs $500 painted and installed with the bars and $400 without.
Hope this answers some of your questions.
Again, we build "METAL YOU CAN BEAT ON!" and these Sliders are sure to pass the test. I Guarantee it!