They are no longer made and are as hard as unobtainium to locate, but I want one for a 12 ga and one for a 20 ga. I will take the kit that has the grip and forend if needed. If you have one or know of one for sale let me know.
We had them on our work 870s till we generally went to a solid composite version or Surefire versions. I did generally like them. I have not seen one in years though.