If your lucky enough to spot one square body in a local boneyard here--your lucky if it has any doors on it period,and if there is,its because that bottom 6" is missing,salted right off,or its stoved in...and the interior is usually either trashed form years of neglect,or "work truck" abuse,,mildewed,etc,or some gorilla has ripped the door panels right off and ruined them,just to gain access to a window regulator..
Unfortunately most of what I've seen for aftermarket replacement dashes,arm rests,etc,are pretty cheesy and nowhere near the OEM quality GM ones were...not cheap either..
Interior repairs are getting insane--you used to be able to get a seat re-covered locally for under 100 bucks,unless you wanted some fancy tuck & roll job...now they want 300-500 bucks to do a bench seat..when I asked how much for a new headliner for an El-Camino I owned many years ago,I was quoted 400 bucks...or if I wanted the original one glued back in place (it was still in decent shape,no rot or rips),the price was 125 bucks...
I decided to buy some 3M spray adhesive,some thumb tacks,and used a few slats from old window blinds painted silver,across the headliner,stuffed into the plastic trim panels,to keep it from drooping down onto my head when I'd go down the highway with the windows open..for under 15 bucks it looked good enough for me..another truck I had,I used that aluminum bubble wrap insulation for a headliner,I spray glued it right to the roof,and it actually looked pretty good..
I'd like to find a decent seat for my truck--the few I've found in junkyards that would fit always have a ripped drivers side just like mine is,some foam missing,and most look like 500 lb sumo wrestler sat on it for 300,000 miles..even just a "restorable" seat with just springs left are in demand ,you just dont see many around..
--I can live with mine as is,the "saddle blanket" seat cover is starting to deteriorate though,and even one of those things now cost 35-50 bucks..only one place locally stocks one,a Pep Boys,and it seems pretty thin and fragile compared to the one in the truck,which feels more like a burlap sack as far as the fabric durability..
Every time I hit up a salvage yard I hope to see a seat cover like mine in decent shape I could snag cheap,but more than once a otherwise nice one I found was used to wipe off greasy hands,or had an engine block lying on the seat,or someone used it to lie under a vehicle ..
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How would I go about fixing my original door panels? 
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