Rattle and Headlight

with the rattling sound it might be quite a few things and many are surprising when I went hunting for the same issue with my X, check to see the passenger seat that tend to rattle as mine did. but check the windshield wipers, yes it sounds weird but if the bolt is loose it might cause the blade to rattle to make an annoying sound. also check out ClubXterra.org lots of helpful tips and advices to help you with any Xterra problems.

have you checked the heat shield over the exhaust system under the drivers seat? i had a similar problem and just removed the shield's. problem solved

You might be having the same problem I did with my 06 Xterra. There is a design flaw in how the exhaust pipes connect to the heat shield. They used these cheap super thin metal clamps to attach the pipe. When your underbody starts to rust these clamps snap and start rattling around pipe. Not only that but now the exhaust pipe rattles because it's not connected. Took mine to the dealership and they ended up welding the pipe and removed the clamps. Fixed me right up! Hope this helps!