can't agree with you more about the noise. The first time I heard it, (2 years ago) I opened up that box and noticed some carbon or some other deposit on one of the contact pairs. I cleaned up the contacts and replaced the components. Have not heard that noise since then. I did open up that box again, but did not see any buildup this time, BUT, the wire that is near the flat metal fuse has melted the plastic surrounding the encapsulated brass bolt that is found in the upper part of that box.... a hex nut holds the wire in place.

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1985 300SD