Now you have me confused
The number 7 fuse should be for the RH high beam headlight, and fuse 1 is for dash lights. If this is true try unplugging the RH headlight then use the light switch and see if that blows the fuse. I also once saw a broken piece of fuse metal cause a ground from one circuit to another in the fuse box, so double check that the box is free from debris causing a short to ground. Let me know what you discover from this. Remember that fuse 1 and 7 should be white in color at 8 amps.
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'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan