As the title of this thread says, tonight I drained the fuel cell, and then threw it away. For the MattMobile, the location of the fuel cell is such that the original cannot be used. It's too big, which makes it difficult/impossible to locate in a new place within the car, which is necessary. So I chucked it.
Looks like I'm also going to be selling the radiator/cooling system for the car, as it is too wide to fit inside the shell. Not totally sure about this, and I will definitely wait for the shell to arrive before I do any tossing or selling.