I just got my In-dash adaptor for my 1997 Mercury Sable, and I was trying to install it. However, the illustrations provided showed a rear support bar that helpsadd stability to the CD unit. However, one was not provided. The ISO mounting brackets seem to hold on fine to the head unit, but should I wait and try to install the rear beam from scrap, or move on? I really don't feel like opening this thing up again.