Wouldn't it just be, push in and pull up on the bottom then unbolt or whatnot from there? I have been in a few GMs and that seems to be how the seats always work. The back seat is always just in some holding hole so push in on it and pull up then unbolt it and it would come out. But don't take my word for fact here, I am just going off of experience from my car and an impala and a couple caddies.