I'm looking for this for you, but apparently not in my head any more, and I'm not finding it right off.... Just for time/effort consideration. Etrack has seven kajillion mounting holes for every inch of track (give or take), but you don't have to use them all to get the load rating. Bolted (nut and bolt through steel trailer member, it's remarkably few of the holes that are "populated". 3/4 inch wood screws into 3/4 trailer walls (the thickness of the e-track keeps them from poking out the other side), then I "think"???? it's every other hole. Rivets (good side on an outside wall) take something in the middle..... I joked about the billion holes, and you'll think it is by the time it's done it's only half a million or so, but there are guides, and honestly, years ago when I did this on a couple of enclosed landscape trailers, it's not a billion holes. It's less. But it's a lot. And they're "real" screws. No tek screws (zip screws, self drilling) can go into wood. Metal only for those. You loose too much thread for the drill point on short little screws, and the pilot comes out oversized and blah blah blah engineering stuff. It's very specific, but nothing that's hard to do or come by, just gotta be right.