If you could show a picture it would help. But on my 93 the vertical metal framing stops at the flat metal strip "outside"where the back one piece panel connects to the side wall. On the rounded corners there is no framing. At the top of the side walls there is a horizontal band where the roof attaches to the side wall. Where you are talking about is very close to where the metal framing would be stopping. The drip rails are usually installed on top of roof edge where it folds over the side wall panel, unless its leaking through a rivet or screw hole, it may be more likely leaking where the end cap fastens in right there.