Preparing to install headliner in 71 Chevelle. The 2nd bow back from the front is shaped differently than all others - it doesn't seem to have as much curve to it. It also does not come within as close to the inside of the roof. It also does not have a "catch" on the side by the hole it attaches to like to other do. Is this normal for this particular bow? Also, if I need to replace that one, are bows the same on '68 through '72's?