Just ordered some for our Charger, it's from Lord Corp, called Fusor 121/124 flex foam super fast.

Had to get an automotive jobber's name from Lord Corp.
Their web page only lists industrial suppliers.
Call Lord (877-275-5673)and press "2" at the prompt and the guy will give you a local automotive supplier

I'm in the Cleveland area and they will have it tomorrow. One tube was about $50.

Joe