I finally got around to making my sliders and getting them mounted. The slider itself is a piece of 2x3x3/16 rectangular tubing with the ends capped. The rear mount is a piece of 2x2x3/16 angle that gets bolted to the outrigger. My outriggers are 3x5x3/16, definately not stock.  So I would reinforce a normal Series frame for this style of attaching.

Side shot of the slider.  When I capped the ends I just cut an angle into the tube.  I should have found a stock sill and traced the lines from that.  It would have made the slider more stealthy.

From the front.  As you can see the slider is flush with the sides of the truck. It was necessary to notch and reinforce the tube around the bulkhead foot. The front mount gets bolted to the bulkhead outrigger.