No mounts. I used four Rhino USA soft loops and two ratchet straps to secure them. Also snugged up one of the factory load bars on the top rung of the rack against one side of the cans. I effectively created a small tight basket for the cans and then strapped them in.

Worked great in that config, did over 200 miles in mixed offroad terrain and about the same number of freeway miles back and forth to the trail from home. On another trip where I only needed 10 gallons, I did similar but laid two cans flat on their sides in the same space.

No issues at all, just have to loosen and tighten the straps as needed to allow for swelling of full cans or shrinkage of empties.