73-87 Square Body Chevy & GMC C/K Truck Buyers Guide (Design, Options, Engines, Common Problems)

Square Body Truck Buyer's Guide! We'll cover the common problems, the specs, and everything else you've wanted to know about the 73-78 Chevy / GMC Trucks!

In terms of exterior design, the 3rd gen CK was a revolutionary design at the time. GM coined the term "rounded line exterior” for this pickup due to the rounded windshield corners, rounded corners of the cab roof, rounded-corner doors, slanted front fenders, and rounded pickup box corners. However, most owners and enthusiasts refer to these trucks are square bodies or box body.

The trucks were only available with a regular cab configuration, except for the crew-cab variant on the 20 and 30 series that offered four doors for 3 more passengers or more cargo inside the cab. The were 2 different styles of pickup beds available. The beds with fender flares were called Fleetside by Chevrolet and Wideside by GMC. They were available in 6.5ft and 8 ft lengths and depending on the year, both wood and steel beds were available. The Stepside by Chevrolet and Fenderside by GMC, was a narrow width flare fender pickup box featuring steps along with standalone tail lamps. Initially, only wood floors were available, but later models received steel floors.

Some other nice exterior elements include the wide front grilles, full doors that extended to the roofline, and the wonderful collection of different paint colors and finishes available. By now, you should have noticed all of the amazing color combinations and paint styles that these trucks were originally finished in. No truck today comes close to giving you all of the nice paint jobs that were available on the 3rd gen C/K pickups.

The interior in this generation of C/K reflected GMs past progressive attitude towards pickups. They knew that more and more owners were using their trucks as daily drivers, so they intended to make the trucks easier to use and more comfortable to live with.

This progressive attitude led to GM fitting this generation with some wonderful comfort features that weren’t usually available in pickups during the 3rd gen C/K production time frame. These included soft-touch materials were used throughout including the dashboard, (armrests), steering wheel, and shift levers. High quality grained interior panels and bright metalwork was used on the inside. Custom Vinyl which was a variant of vinyl or soft Custom Cloth and velour seating surfaces were used. Additionally, there was fabric headliners, door inserts, and deep plush carpeting, depending on the trim level. Higher trim levels used sound-deadening materials for quieter ride comfort. The wraparound dashboard had a full complement of gauges. There was an optional all-weather HVAC system with Air-conditioning that had the vents integrated into the dashboard, and owners could option an AM or an AM/FM radio with the radio antenna integrated into the windshield for a sleek look.

The GMC was available in Sierra, Sierra Grande, Sierra Classic, and the top-of-the-line high Sierra trim. The Chevrolet was available in custom deluxe, Scottsdale, Cheyenne, and its’s top-of-the-line-model, the Silverado. The high trim levels were plusher and had an emphasis on comfort and luxury.

In terms of engines, the third generation CK offered six-cylinder and eight-cylinder power plants as well as some Diesel engines. The entry-level six-cylinder was a 250 followed by a 292 six-cylinder. The 8 cylinder gas engines were available in 305, 350, 400, and 454 cubic inch displacements. The two diesels were 350 cubic inch and a 379 turbo diesel.

Looking at the data, you can see that the horsepower and torque figures are pretty low when compared to today’s engines. This is due to the fact that there was an oil crisis and as well as a strong push to get lower emissions by any means possible. These factors contributed to to create an era of low powered vehicles across most manufacturers.

The 4wd K-Series pickups were available with 3 different systems: a Conventional, a Permanent, or a Shift-on-the-move four-wheel-drive that was introduced for 1981. All K-Series pickups featured four-corner Vari-Rate multi-leaf springs, front live axle with symmetrical (inline) shock absorber geometry, and the Load Control rear suspension system. The 4wd pickups featured a transfer case that was bolted directly to the transmission and driveline components were installed as high as possible to reduce the chances of the undercarriage hitting obstacles, and to achieve optimal ground clearance. Steel wrapped Brake lines and an underbody skid plate optional.

There were lots of great options available on the C/K Pickup trucks. They included niceties like blow eye-line mirrors, power windows and locks, a tilt steering wheel, AM/FM stereo with cassette player, sliding rear window, fuel tank shield, rallye or styled wheels, A CB radio, cruise control, and deluxe or special two-tone paint finishes.

Watch this video to get the full scoop on the 73-87 GM Trucks!

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[ianisaacs]

I own a 74 c10 I got 5 years ago when I was 17 for $2, 800. Still has the factory 250 inline 6 with a 3 on the tree transmission. (Love the old school vibe and none of my friends ask to drive it!) It has the option tag intact and shows a few upgrades the original owner selected like a heavy duty clutch and rear springs, chrome front bumper, radio...If I have my say I will never part with it. I feel like I’m driving a couch it’s so comfy. It only left me stranded one time, the ignition coil went bad. So I got electronic ignition and she’s all good. She’s my daily driver and still earns a living on my pool route! I rate her ⭐️⭐️⭐️⭐️⭐️

[NyuuMikuru]

Yes. Easy oil change, easy sparkplugs change, easy work on engine, easy works on engine parts unlike today’s truck which you cannot.

[Southernson-dynq]

Owned my 85 c10 since 1989. In the process of restoring it now. Love my Square Body !

[milesmayes]

I’m 16 and just bought my 78 Scottsdale and I’m so in love with it

[Invisibleindreamsonly]

My dad bought a 1973 Chevy Cheyenne super 10 for his 40th birthday and it had the blue and white combination paint!!!
I remember as a kid when I first rode in it with its 7and a half inch thick bench seat a 350 engine and I knew then that this was a special truck that would stand the test of time.
We lived on the water and unfortunately the salt water wasn’t too kind to the body with rust starting I think about 6 years or so later but how I loved that truck !!!!
It was the engine that I performed my first tuneup on and later some of my first Autobody repairs on but how I loved that truck!!!!
Now here we are almost 50 years later and just as I knew then it continues to be one if not the most sought after trucks by collectors today.
And as I think back now to my dads truck all I can say is how I loved that truck!!!!

[benjaminhutchins]

I own an 84 Silverado K20, 140, 000 miles on it. I will be keeping this truck for the rest of my life. Coolest trucks ever made by far.

[richardrichard]

My wife and I own my father in-laws 1973 GMC 2500. He bought it in 1972. Rust is a big problem and we live in Ca. I just painted the exterior and am in the process off refinishing the interior.

[johnnyhawk]

I have a 1977 c10. Have owned it for 38 years. Have owned it longer than anything I have including the wife and kids. Still runs great and I will own it till the day I die.

[burnsred]

I was 19 my very first vehicle ever was a 1977 C-30 w/350 V8 and 4spd manual I bought used my mother was less than impressed it had no bed on it my father built a wooden flat-bed for it and the rest was history I loved that truck!

[kellismith]

I have driven many different fords and chevs both from that era and newer, none of them could match the reliability of the 1984 c10 I drove for 25 yrs, a few things failed but were easy and affordable to repair - no other model even comes close
IMO those were the best trucks ever built

[P]

When I was in high school around 1984 my dad picked up a 1974 GMC 4 x 4 stepside, it had a 350 and a manual 3 speed with Granny Gear. That truck would kill anything made since. ;-) One time when we were getting on the highway about to make a 300 mile trip towing a boat the transmission lost a few gears, turns out it was something to do with the part time 4 wheel drive and the local 4x4 shop had a retrofit kit that fixed it, my dad and I did this all in our driveway. My dad also took this truck out hinting shortly after buying it and the factory manual hubs wouldn't lock, so my dad was able to get a set of Warn hubs and put them on in the parking lot. Another thing we did in our driveway was put on a Rancho 4" lift front and rear.

[mattvarricchio]

Purchased my 1987 c/10
Custom deluxe - 3 speed w OD, note I have never heard of another or seen a 3 speed w OD on the floor outside the one I had . bench seat 305 throttle throttle body fuel injection two town paint special I think you call it . I drove it till 2013 last two years as a farm truck - 108k if memory serves - other than a battery and one clutch - I can not remember one single time it broke down or failed me
NOT ONE . ILL never beat that run . Great truck the bed & engine both solid as a rock the day I sold it to couple boys after a year of pestering me for it . Great video

[paulmarentette]

I bought a 75 Silverado no-reserve at an auction. This was Chevy's first year to introduce the top Silverado trim level, and followed two successful model years since the redesign. Our truck at auction had never been winter driven, was low mileage (but not so low as to sit for too long) and looked great in that iconic mid-70's two-tone Grecian Bronze (burnt orange) and Frost White. Interior had a reasonable go-over with no cracks or issues. THE BIGGEST SURPRISE WAS HOW WELL IT DROVE! Quiet, composed, and straight as an arrow. We did several long, cross-country drives, including one from Toronto Ontario to tow back a '79 Airstream Sovereign we bought in Florida, which it did with style and ease. We're in the process now of a full restoration, which is not inexpensive, but we do look forward to another 15 years or more of enjoyment from our truck. We don't need a full time truck, so this vintage one fits the purpose and it seems we get more thumbs-up driving it than even my '65 Sting Ray convertible. It's a real head turner!

[allenminer]

Bought my 1984 K-10 Custom in December 1983. Still driving it. I get offers to buy it all the time.

[stanhagaman]

I bought my 1975 3/4 ton 4wh dr. in 1978 and I STILL OWN AND DRIVE IT!!! It now has over 530, 000 miles on it!!! It's the toughest truck I've ever owned!! Although I've changed engines and transmission, the original motor and transmission were working properly when I took them out! Instead of the 350 cu. in. motor and 350 turbo trani. I installed a 1975 500cu. in. Cadillac engine and 400 turbo transmission with out any trouble!! Believe me it put the fun back into driving it!!! If you want to go a little faster just push down on the gas pedal (LOTS-O-POWER) The truck still looks in super shape!! (No rust!) And unless someone offers me a stupid amount of "cash" I'll still have her when I throw in the The ride is a little stiff but a great truck period!!!

[weskirkland]

GREAT VIDEO! Paused it a lot to read. I've had 3 of these things. Never had any other truck since I started driving in 1996. Had a 77 Chevy Sport, an 87 R10 and Now have a 78 C20.

[brandonbell]

These are excellent trucks. I just picked up a blue 77 GMC shortbed still running and driving original 350/3504 barrel and has the original dealer sticker on the tailgate

[badbob]

I have a 74 k-10 with a 3/4 ton upgrade. 25 years ago I though of selling it but I read the option list in the glove compartment. About 34 years I have owned it. It has been on 90% of the back roads in Arizona, never let me down, or been to a shop. I will start up the new rebuild 350 I put in tomorrow, Friday and I plan to be out in the desert Saturday ripping it up.

[cerescorubi]

Bought my 1977 new and kept it until 1997. It was a great truck. I Zwibarted it when new and still almost norust 20 years later. Forget the miles but at least 150, 000. Replaced so many parts over that time but it took care of me until I quit maintaining it during a period of two jobs and little money or time. Russet color.