I remember seeing a jig that looked like a craw with a head that resembled a tail, it had to be a custom but I think I know what you mean. The wobble jig mold had a couple variants, there was one with a barbed collar and one without if I'm not mistaken, We used to use the grave digger jig to fish soft plastic grubs for river smallies, the shape of the jig would cause the grub to move side to side and it would get bit on the tough days. The wobble head made a great bottom crawling jig, I wish I never sold it.