31 Pickup Top Wood Question

[Nasukau]

Hi All,
I just started to remove all the rotten top wood on my 31 CCPU and I am noticing some type of cloth or weather stripping between the metal and the wood. Was this something done from the Ford factory or someone replaced and added this? If this is factory what is the material called as I would need to order some for my installation of the new wood. Also do I need to treat this new wood with anything before installing?

Thanks,
Denny