Air cleaners. I did not have much to choose from the trucks I had, only one under hood that was in poor condition. I purchased a NOS under hood kit as I thought it looked more "Military". After installing it the first thing I noticed is that it was right in your face when trying to do anything under the hood, I quickly hated it. So I purchased a NOS first type air cleaner from Saturn Surplus, much cleaner and more room to work around.