It also has a tab for an electrical ground with yellow paint on it. Not sure that paint is original--don't know about the part as a whole, though.
Looking at
Jeff Bowlsby's 914 Tech Notebook page turns up a diagram of where the ground on the car are:
The only one of those I don't have a mental picture of is the ground up behind the instrument panel. It's possible this is that ground, but I kind of doubt it. It's not any of the others.
--DD