The yard I go to most often has had more 67-72 GM's than square bodies lately,but all were shells,completely boned out..
I don't recall ever seeing a K5 of that vintage (first gen) in a salvage yard even back in the 80's..people hung onto them forever or stashed them "out back" in their yards rather than sell them to salvage yards,many got parted out "privately"...used to see lots of '73-87 K5's 15 or so years ago in salvage yards,Burb's and pickups galore too..that period some years back when scrap went up to $250 a ton or more made all of the old iron vanish rapidly..that cash for clunkers took a lot of trucks off the used market too..
Most yards here dont keep much if it is over 10 years old..20 at the most,and only "popular" cars that there are still many of on the roads..
One trip to my favorite salvage yard about 10 years ago revealed a new arrival--a 1964 GMC panel truck--3/4 ton 4x4...it was rough,looked like someone started sanding it down,slapped on some bondo over rot patches around the rear wheel arches and quarters,and abandoned it--was surface rusted all over and had some rot on the door bottoms and the floors had a few patches,but nothing extensively rotted ..
I was able to read lettering on one side of the truck--it was a former fire truck from some town in RI,I couldn't make it out,I think it was Tiverton...it had those big ugly diamond plate bumpers and looked like it had a winch on both ends previously..
The inside was FULL of parts,at least 3 small blocks ,heads,drive shafts,another transfer case (Rockwell),and SM 420 tranny,and there was only front seats but they were only springs with no padding left really..it also had the earlier "eyebrow" hood...
I opened the hood and saw a 283 with a Edelbrock carb,all white as a ghost..had a 4 speed too!..was still solid where they always rot at the hood hinges too..
You could tell the truck was real nice at one time,most fire trucks get pampered and are parked indoors--someone must have got it at a town auction and left it out to the weather for 15+ years..
I about cried seeing that thing sitting there--I asked the guy at the office if it was for sale,he hesitated and said "why--what do you need"?--I said I was interested in the whole truck,and wondered if it was titled--he said "Um--we're not sure what were going to do with that yet--it really shouldn't have been put back there in the pick & pull area,we had to move it out of the parking lot to manuver a 18 wheeled flatbed the other day"...
"Also I know we don't have the title,and most likely you wont be able to get one for it"...If we were to sell it as a whole,parts and all--we'd want like 4 grand for it"..
Two weeks later I went back there and saw a Mazda sitting on the roof of the panel truck...

...the guy at the office said "Someone put a down payment on it the other day--sold it for $3500,he didn't care about no title..he agreed to pay 4 grand ,until my stupid loader driver put that Mazda on top of it so someone could get the tires off it!..the guy was livid,but still wanted it,for less money"..