This past weekend I decided to tackle the my rear hatch window leak that I've known about for about 10 months. I decided that rather then just seal up the window with urethane, that I would instead replace the gasket. I did this to make sure that the leak would be gone, but also to check up on the sheet metal pinch condition where the gasket seats. I was concerned about rust since this is the main area where 80's like to rust. Water gets under the gasket and then in between the pinch where the two halves of the hatch are pinch welded together. Toyota didn't put any sealer or weld the area up tight since they never expected water to get past the gasket, and really it shouldn't since the window should be sealed like the front window with urethane between the body and gasket and urethane between the gasket and glass. First some history on my truck. My truck lived 7 of it's years in Las Vegas, NV and then lived in Northern California after I bought it for about 3 years. Now it lives in San Antonio, TX. Non of these places are salt areas, however the latter two definitely have more rain than Las Vegas. So seeing that this history of my truck I wasn't that worried about rust. I can now say I'm very glad that I decided to take the window out. After taking out the window I noticed that rust was starting to form in the areas that the leaks were occurring. The biggest area was the bottom passenger side corner. I was able to clean it up with some 00 steel wool and mineral spirits. I'll post some pictures later when I find the usb cable for my camera. After the cleanup I sealed the gasket to the glass with urethane, installed the window, and then sealed the body to the gasket with more urethane. So I think the lesson here is that this area is a rust magnet, however if the seal on the window is good there should be no reason for rust to occur. If your window is leaking I would suggest you fix it... and if you have external rust, well I feel for you.