Doug, the feet have 4" by 4" plates that weld to the floor and the tube welds to it. I'll get a picture of that stuff tomorrow too. I have to paint it all up tomorrow.
Make sure you add some bracing under the plates.... I didnt and it ripped my floorboards apart over time. May be fine for a while but after 2 years I had to add some pieces between the unibody and my sliders..... Unless you welded the plates over the unibody rails.
The front 2 and the back two are directly over the unirail. There's two on the back fenderwells and the b pillar posts are about 3 inches outboard of the unirails. Most of my floor has been replaced with 1/8" thick sheet metal. Ill watch for signs of wear. Thanks for the headsup.