RE: what do I call it
That's a muckempluckem board with a frizzledadoodlag groove in it. Too bad your LHS guys couldn't figure out what a freaking landing gear block was from your description. Some of the guys in mine aren't capable of doing anything but looking up a part number for an ARF part or getting boxes off of shelves. If you ask them to be creative or actually solve a problem, they look at you like you're speaking Greek.