If no one knows do a burn test on a small  piece you can trim off somewhere:
http://www.northwestpolymers.ca/index.php?option=content&task=view&id=18
I'll bet it's polystyrene, but I don't know.

Stuart

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Cunegonde
Sent: Monday, February 17, 2014 4:29 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Front Heater Box Plastic Type

Anybody know - ABS, PE, Nylon... ? I need to repair some cracks & busted
tabs, have to use correct plastic welding rod or cement.