Looks a bit tougher than the old velvet rides, Sulastic spring shackles are 1/2 the cost and no holes need to be drilled but don`t look as heavy- duty as these. Is ride height mantained or does the truck sit lower? Somebody needs to try these and report their thoughts.
It looks like a varient of a shock. It just helps dissapate the spring energy. NOT FOR HELPING CARRY LOADS