Back in the day the "roofing felt" type of product we used to install these came in 3 or 4 different thicknesses.. We would then paint a petroleum product ( we used kerosene) on it after install as it would thicken as it soaked up the kerosene..

Also another product available was "cork and rubber" which was like cork gasket material...

Maybe visit an auto glass shop and get some of the correct material before you have to "redo" ( I saw LOTS of em come apart ) it..