I have seen some bench seats for sale that clame to 'retrofit' my 97 Tahoe with a rear-facing 3rd seat. Are these legit? How can I find out if I can mount one in my truck?

Check out e-bay. A surburban rear seat will fit in the back of a standard size tahoe. They are about $600 with shipping and brackets. I am doing one right now. Hey, it even matched the interior.