Has anyone ever figured out what the little tray that attaches to the left side of an M-04 was supposed to be? I've flipped through several M-04 assembly manuals and the part never seems to get used anywhere. At the time they designed them, there weren't any electronics small enough to fit into that thing. Might be a good home for a micro receiver now, though.
Maybe Tamiya's engineers can see through time. (backwards, most of the time. So many re-releases.)