Has anyone ever replaced one of these? If so, where did you find one? I can't determine if it is a Cummins part, Freightliner part, or specific to Monaco/HR. This is what happened to it:
You need to find the engine ID plate (located on the timing cover) and copy down the numbers on it. From that, Cummins can get you any part that was originally used on their engine.
Looking at the part, you may be able to unscrew the socket head and just use a piece of all-thread to replace it.