On Cougars, the arm rest attaches to the rear panels, not into the steel structure. Just bolted onto the molded plastic panels, a bit of reinforcing behind there too. Not real sturdy.
I should know this, but not positive. Three levels of Cougar interiors, standard, deluxe, and XR7. Standard's do not have the arm rests, XR7's do. Not positive on the deluxe interiors.