I replaced all my '67 Overlander's seals in 2004 and everything is still good. You can read about it here:
http://home.hiwaay.net/~tomorkim/WindowSeals.htm
Of note:
* every couple of years the windows are opened so the seals can be sprayed with silicone spray.
* While Inland Andy sold me the double-lip seals, his store now only sells D-seals.
* To seal hinge leaks, Inland Andy recommended pumping RTV into the hinge & operating the window to distribute it.
Hope this helps,
Tom