No you dont have to get one from the dealer. Ive dropped one of those! There a bastard to find. What i did, was take the other side off and take it to the hardware store and match it up. Dosnt have to be brass. I would put some dielectric grease on the bolt/screw to prevent corrosion. I also bought a couple just for spite.
Next to the 10mm socket I imagine.Thanks for all the replies! Yep that thing fell into the black hole...