Finally built some sliders for the runner the other weekend. They're pretty simple in design. I had u bolts bent up that fit around my frame which allowed me to easily bolt the sliders instead of weld them to my frame. Main tube is inch and three quater .120 wall, and outer tube is inch and one half, also 120 wall. The mounting plates are 1/4" thick with 1/8" flat stock wrapped around them to keep them from flexing when being tightened down. 1x3 tubing was used to connect the mounting plates to main tube. Well anyways heres some pics.
Mounts:
Mounts: