I bought an 06 FX4 screw with the power slider rear window. Its been leaking every time it rained since I got the truck from the back edge of the headliner onto the back seat. At first I thought it was the terrible third brake light problem but after buying a new one and replacing the old one, I was still leaking. I water tested the light and examined the inside and couldn't find evidence that was the culprit. So I ran water down the weather seals on either side of the slider, this caused substantial leaking.

The back window was obviously replaced before, the signs are all over. I guess they didn't do too good a job of sealing it up. There's about a 1/8 in gap between the weather strip and the back of the cab. I figured this was just a runoff to the sides of the window, but putting water down inside it leaks into the cab.

Is there a reasonable solution to this aside from taking the window out and resealing it?