[Mike C]

Congrats! Adding a middle belt should be fairly straight-forward. It attaches to the inner bolts for the two outside belts. At least on my truck it did. I have a Suburban for parts but don't remember if I pulled the belts out? It was missing the rear seat. I will have to look and see if it has a center rear and how it is mounted. A good fabricator could build a frame that attached to the seat bolts and followed the back of the seat for the upper restraint attachment.