I went out and examined my taillights and I can confirm that Under the plastic covers, the right side lower right bulb holder (the one that doesn't light) is white plastic, the drivers side is black. I had the brake peddle down the while I was checking things, and I unscrewed every light and put them back in. The only one that looked caroded was the left side lower left bulb. The connections seemed good, and also the two black wires on each side appeared tightly screwed to the body. The white clips that attach wires to the lights appeared clean as well. I unhooked these and blew them out. Also, I do not have a trailor hitch. Hope this information helps you. Thanks again! Rachel