Don't hold what I say as gospel as its been a number of years since I've messed with trucks, but, I think that is a fuse panel for an '81-'82?

'72 - '80 had the fuse panel mounted at the top of the dash next to the glovebox.

'81 was when the trucks got their face lift (and a new dash) which moved the fuse panel under the dash to a more conventional spot.

I'm thinking the first two years had the old style fuses then in '83 or '84 switched over to the blade type panel.

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