They were usually about 1/4" thick but seeing the size of the glass it might be more. I never had the pleasure of replacing one of those but a 2 man job to lay it in place then it's all yours lol. The good news is that the new rubber will be soft and pliable. Use some liquid soap on it when installing. Make it so much simpler. Do you have the tool to install the lock strip? You can make one. If you want an example of mine I can post it.
