I'm not up to speed on that year, but several years shared the same sheetmetal. You should be able to find the same or similar at salvage yards, body shops, and there are many online vendors like Roberts and Vintage Power Wagon that could lead you in the right direction.
Bed sides and tailgate (so effectively the whole bed), fenders, doors, and possibly the front valence and radiator core support should be the same '81-'93.
Grille changed in '90 or '91, and so did the mountings for the lights. It's possible that the core support changed too, but I don't think that it did.
Hood was revised in '79 and I think remained the same through '93.
Cab, bed floor/inside/cab protector are vastly similar '72-'93. The rear window opening changed a few times.
I don't know about fender liners.
The stepside beds had wood floors earlier, metal floors later.
The frames are different on the very first trucks ('72, maybe '73); I know this because of Cummins swap discussions- the Cummins doesn't fit into the first year (or maybe two) while it does fit into everything else of the same weight class.
Around here (Phoenix area) there are lots of trucks and parts available, in varying condition.