I heard strange noises under my 98 Tacoma (4 cyl, 2.7L, manual), checked it out and - lo and behold - somehow the nuts had unscrewed themselves from the posts that hold the O2 sensor on the exhaust system.
Last thing I'd want to do is pay an arm and a leg for a pair of nuts, at least this kind. So I'm going to the local hardware store instead of the not-so-local nearest Toyota dealer.
Does anyone know the size of the nuts (diameter, thread) I need for these posts?