GM-GMC: seat belt, alarm bells, seat installation

Question
I recently bought a 2003 Chevrolet 1500 HD silverado and the back center seat belt is not fastened underneath the seat can you explain how to fasten it or show me a diagram on how its suppose to hook up? Thanks

Answer
Their should be some alarm bells sounding here for a couple of reasons.  1) why is the seatbelt not hooked up in the first place and 2)how would that pass a safety inspection? (assuming it had one)

To answer your question....
Remove the rear seat

Installation Procedure

Install the buckle assembly to the floor panel stud

Install the nuts to the buckle assembly

Tighten the nuts to 42 N·m (31 lb ft)

Install the rear seat

Hope this helps