I did get a spot of rust back there; as I understand it the window gasket back there shrinks & lets in water that stays right in that area.
I had the window removed, and the area properly repaired. No recurrence, and it's been a year
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car