When talking about iconic pickup trucks, the conversation will always steer toward one of the most successful lines in truck history. The longstanding Chevy and GMC C/K series spans over six decades, from 1960 to 2002. But, there is a strong chance that a big part of that debate will focus on the popular third-generation 1973 – 1987 Chevy and GMC C/K models, known as Square Body trucks.
Square Body refers to the series of C/K trucks that debuted in 1973. They immediately rose to fame, paving the way for an impressive 14 years of continuous production — without any major redesigns. A wide variety of models were offered, including light, medium, and full-sized pickup trucks and SUVs.
Select Square Body models, such as the Blazer, Suburban, and dual-wheel pickups, continued production until 1991. But generally speaking, ’73 – ’87 is seen as the primary years of production for Square Body trucks.
History
C/K terminology is straightforward, with “C” denoting two-wheel-drive trucks, while “K” signifies four-wheel-drive variants. Meanwhile, the numerals 10, 20, and 30 represent weight class, breaking things down by half-ton, three-quarter-ton, and one-ton, respectively. For example, a C10 model is a two-wheel-drive half-ton pickup.
Interestingly, while the public quickly bestowed the nickname Square Body on the third-generation C/K trucks, it was officially known as the “Round Line” style by Chevy designers. However, compared to prior generations, its boxy body style lent itself to the colloquial name.
It was a radically different design from previous iterations of the C/K line. The new trucks aimed to improve visibility with larger glass areas and curved side windows. In addition, the windshield, door frames, and square wheel wells all feature rounded corners, hence the name “Round Line.”
What helped propel the Square Body’s popularity focused on creature comforts with more elaborate dashboards and interiors. A far more spacious cab was complimented by cushier seating, increased airflow, better insulation, and weatherproofing, which improved the driving experience.
Four-door crew cab options were also available on select models, making them appeal to wider audiences.
The Square Body also introduced an all-new chassis that offered superior ride quality. Longer wheelbases helped increase stability, while frames featured additional bracing. In addition, staggered rear shock absorbers and leaf spring geometry were revised, to name a few of the changes.
There were a total of five engine choices offered across the C/K range. 250 and 292 inline 6-cylinder engines were common in light-duty trucks, while others used 307, 350, or 454 V8 engines.
Popularity
Total production numbers for Square Body trucks are difficult to pin down. However, it is estimated that over 10 million units were manufactured, and plenty of fine examples are still on the road today.
Initially, these trucks were incredibly popular with tradespeople due to their robust nature, hauling capability, and variety of powertrain options. Their massive production volume made replacement parts easy to come by and relatively affordable.
In fact, most auto parts suppliers still supply common components for C/K models, despite their age.
LS Swap Fuel Pump Hanger w/ 6AN Fittings for 1973-1991 Square Body Pickup, C10 / C20 / C30, K10 / K20 / K30, R10 / R20 / R30, V10 / V20 / V30, QFS-H880
Fast forward a few decades, and the Square Body has moved from the role of a farm or construction workhorse to one of the darlings of the performance truck world. A thriving Square Body community exists where owners lovingly restore hot rod, mud bog, autocross and do anything imaginable to these trucks.
These are simplistic trucks that most home mechanics can build up in their garage, upgrading chassis, brakes, and engine components without serious modification. Combine a vehicle range available in high numbers with massive aftermarket support, and you generally have a winner on your hands.
The massive engine bays of C/K trucks are appealing for those going the performance route. Engine swaps for modern high-performance LS or LT engines are easy to net huge gains in horsepower and torque without too much trouble.
LS / LT Swap Solutions
Of course, if you’re doing an LS or LT swap in your 1973 – 1987 Chevy and GMC / K10 / R10 / C20 / K20 / R20 / C30 / K30 / R30 / V10 / V20 / V30 truck, you’ll want to install our LS/LT Swap Fuel Pump Hanger and Sending Unit. Our brand new 6AN/6AN hanger is a clean-sheet design meant to facilitate the installation of braided AN hoses without adapters and without splicing wires — saving you time, effort, and money.
Every kit comes with two wiring pigtails compatible with AC Delco EP381, Walbro 255LPH, and other 340LPH intake pumps. Quantum pre-assembled fuel pump hangers feature a lifetime warranty on the Quantum fuel pump and sending unit. This is the last hanger your LS/LT swapped Square Body truck will ever need.
Do you have a newer-style GM truck? We have fuel system upgrades for those models as well, read our detailed post about Reviving Your GM 1500 Series.
There is no doubt that the truck market is seeing renewed interest in the third-generation C/K Square Body trucks. We’re excited to see how a new generation of owners will put their spin on them. For all of your fuel system needs on your C/K truck, be sure to check out our web store. All orders placed by 2:00PM PST ship the same business day!
Frequently Asked Questions
“Square Body” refers to the third generation of Chevrolet and GMC C/K trucks built from 1973 to 1987. The nickname comes from their boxy, squared-off styling with straight lines, flat body panels, and a rugged, no-nonsense appearance that became iconic in American truck history.
Square Body trucks were produced from 1973 through 1987 in the United States. However, some continued production in international markets beyond this range. Their long run and popularity made them one of the most recognizable and collectible truck generations ever built.
Square Bodies are admired for their durability, simplicity, and classic styling. Enthusiasts value their strong frames, easy-to-modify platforms, and abundant aftermarket support. Collectors also appreciate them as symbols of American truck culture, with rising demand making them sought-after restorations and restomods.
Square Body trucks were offered in multiple configurations, including regular cab, crew cab, and chassis cab options. Bed styles included Fleetside and Stepside designs. These variations allowed buyers to choose between work-oriented trucks or stylish, recreational pickups that fit a variety of needs.
Engines ranged from inline-sixes to small-block and big-block V8s. Popular options included the 250 I6, 305 and 350 small-block V8s, and the 454 big-block. Diesel engines were also available in some models, offering versatility for work, towing, and performance needs.
Yes. With available four-wheel drive, heavy-duty axles, and robust suspension setups, Square Body trucks were capable off-roaders. Many models became popular for ranching, farming, and outdoor use. Today, they remain favorites for off-road builds and lifted custom trucks.
The Square Body featured sharp lines, slab sides, and large windows for better visibility. It struck a balance between utility and style, offering comfort upgrades while retaining rugged truck durability. This design became a cultural icon and influenced truck styling for years.
Yes, Square Bodies are highly collectible. Prices have risen steadily as enthusiasts and restorers seek them out. Original, rust-free trucks fetch high values, while modified and restomod versions appeal to performance enthusiasts looking for classic styling with modern drivability.
Restoring a Square Body is easier than many classics due to their simple construction and strong aftermarket support. Parts are widely available, from sheet metal to performance upgrades. With basic mechanical knowledge, many enthusiasts successfully restore or customize these trucks.
Enthusiasts love Square Bodies for their mix of vintage styling, mechanical simplicity, and rugged reliability. They’re versatile platforms for restoration, modification, or daily driving. Owning one connects enthusiasts to a golden era of American trucks, where form and function blended seamlessly.