Mine was leaking heavily from the forward area below the rear window. I sealed the ENTIRE back window glass-to-rubber union with black marine sealant. Also sealed the top and sides where the rubber contacts the body with the same material. No leaks since. Prep is very important, as a lot of gunk settles in there which will make the sealant not work. Several hours of cleaning with rags, alcohol, and popsicle sticks is required.

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma