Hi all, I'm in the process of welding new floor patches into my '82 Custom Cruiser, and I was wondering what material is placed over the floor metal around where the seatbelts bolt in? (see photos below) I'm assuming something like Dynamat would be used to replace the large black pad, but what is the adhesive "Sealing" sheet around the bolt hole? Just simple butyl rubber sheet? Some of the jute over the rear floor plugs also seems to be stuck on with a similar material. If I redo everything with Dynamat, would I need to bother reapplying those small pieces around the seatbelt mounts first? Thanks for the help.