We've used pan head screws and or sickle bolts with good success over the years. We now use the 1_4" pop rivets since we have the air gun to pop them. Be sure to mark the seam of tube on both the swivel and end support before cutting rivets and install new tube with seam in the same spot. Tube can fit snug to swivel so line it up as good as posible to rivet locations before starting to pull on. We pull it on or help get it started by putting a bar across studs on swivel so we can hook a chain to it. We run the chain threw tube and tie to a come-a-long that is secured to something that tube can butt up against. That will help keep a little pressure on things while starting swivel onto tube. Of course we are doing this on the ground. Good luck