I'm a big fan of the triangulated four link & wishbone suspensions. The benefit of them is they don't use a track bar or watts link to help keep the axle from moving side to side. Also mounting the bags about 1/2 way down on the link or using a sleeve bag over the axle is the only way to go if you want a smooth ride. The picture is not a 67 - 72, but it's a triangulated four link with the bags mounted 1/2 way down on the lower links so you can get the idea.