Yes I have seen it , you need a 3-4" tall trangle bracket generally doulbe shear so 2 plates & a rod with rod ends linked from the diff straight forward or slightly downward to the frame rail , of course the frame rail needs to be re-enforced , clamping the front sectiion of the leaf with a square U bolt will help to stiffen the leaf as well
this sytem is often used on 4x4s as well for traction