Where can I get the rubbery foamy thingmagig that goes on the inside of tailgate?!

One of these is missing on my tailgate. I guess its to cushion the blow when closing the tailgate. It looks like it should be glued on. Where can I get one please? Don't even know what its called!

Not sure what you mean, do you have a picture of the one you have?

these have been NLA for years, I can get a part number but it wont help as googling it gives nothing, not even a pic

so its a case of find some suitable foam and use the old one as a template (with some creativity to try and figure out the original shape ) then a bit of contact adhesive to bond it to the tailgate