It's not the correct size or model, but these Gloria fire extinguishers are good to have and are brand new. You'll need to get the correct mounting brackets for them, which are chassis-specific.
Shown in my W123 and W201, at the factory locations:
Maciej over at BW sells them from Poland, shipping takes +/- 30 days due to handling nature of these extinguishers.
http://www.benzworld.org/forums/w124-e-ce-d-td-class/1458159-gloria-fire-extinguishers-available-13.html