The license plate light thingy on the E53 is just a painted trim piece held on with a couple of screws - like, well, a light fixture ('cause that's all it is). It has 2 bulbs over the license plate - one on the left, and one on the right, relatively speaking. Because of the design, you really can't thread wires through from the driver's side of it where the connections are internally to the passenger side light bulb socket. (well, I couldn't, but I wasn't about to make a career out of the thing). I don't know what it's problem was - cleaning the bulb contacts with a pencil eraser usually works well if there's some surface crap, but in this case, multimeter showed it didn't have 12v on the passenger side at all. Dunno what connections may have been buried in there but was easier and quicker to drill a small hole, grommet it, and tie both sides together.

Grommets? We got this local hardware store - locally owned place - is one of those that has aisles upon aisle of interesting stuff, and a whole section of those little multi-compartment boxes you pull out, open up, and make yer selection.

However, unless I'm mistaken, even places like maybe an Ace and perhaps similar have a selection of less-than-mainstream fasteners and stuff, where you pull out the box/tray, open the lid, and fill your baggie. This place, and I'm sure other stores, all kinds of stuff like o-rings, grommets, bushings, nylon odds and ends, etc.

Note to SkidmarkX5 => I'm talkin' 'bout C&H here.