Americans love their trucks, as the continued success of the Ford F-150 attests. But it hasn’t always been like that. Back in the 60s and early 70s, customers viewed their trucks as basic work tools, and not necessarily as passenger vehicles. GM vied to change that with the introduction of the third-generation Chevrolet C/K series in 1973. The square body Chevy, as it became known, was arguably the first truck designed with the end user in mind. This meant a single vehicle could now serve as both a workhorse and an everyday driver. Customers loved this kind of versatility, which forced competitors to follow suit. This manufacturer's arms race sparked the truck craze that continues to this day.

The Square Body Was A Bit Of A Misnomer

A rear three-quarters shot of a red and black 1978 Chevrolet K10 Silverado.
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The colloquial term “Chevy square body” refers to the third-generation Chevrolet and GMC C/K trucks manufactured between 1973 and 1987. Introduced as the follow-up to the “Action Line” trucks of 1967-1972, the trucks were the predecessors to the 1988-1998 GMT400 “Original Body Style” generation. The nickname comes from the very… well, rectangular shape of the bodywork. Want to hear the funny part? Chevrolet actually referred to this generation as the “Rounded Line”. We have no idea what Chevy engineers were on when they came up with the name, but their definition of “round” definitely doesn’t match ours. Either way, the looks of the Chevy square body trucks are timeless. The rectilinear lines with soft edges give them a muscular street presence, while the boxy shape also maximized the glass area, which is one thing GM wanted with this generation. This increased cabin space, contributing to a more comfortable environment for passengers.

Related: This 1972 Chevy C10 With An LS3 Engine Is The Ultimate, 570-Horsepower Street Truck

Advanced Development Tools For The Time

Side static shot of a black 1979 Chevrolet C10 Cheyenne.
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Development of the third generation C/K made heavy use of computers, the first time for a new Chevy truck line. Components were extensively simulated before prototypes were actually made, saving development time and costs. Aerodynamics was also a very important consideration, with considerable time spent on the wind tunnel. A new curved windshield and side glass design resulted in a more efficient shape, which helped save fuel, and a quieter, more comfortable cabin with better ventilation. Chevy integrated the radio antenna into the windshield, further reducing noise levels.

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A Multitude Of Variants And Trim Levels

Front three-quarters shot of a 1984 GMC C1500 Sierra.
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The third-generation C/K series spawned a lot of variants. The C and K in the model’s name stand for rear-wheel-drive and four-wheel-drive, respectively. Therefore, RWD models carried the C designation, while 4WD versions formed the K-series. The Chevrolet trucks further carried the 10, 20, and 30 designations for half-ton, three-quarter-ton, and one-ton trucks respectively, which relates to the approximate nominal payload of the vehicles. This means a C10 is a rear-wheel-drive, half-ton pickup, for example, while a K30 is a one-ton, four-wheel-drive truck. Meanwhile, GMC trucks were initially called the 1500, 2500, and 3500 series, respectively, eventually acquiring the 15, 25, and 35 designations. Short- and long-wheelbase variations, as well as several different bed dimensions, further increased customization options. Chevrolet initially offered the square body in Custom and Cheyenne trims. The former were more basic trucks aimed at working customers, while the latter featured more comfort and aesthetic equipment, and were meant for personal use. Later, the Scottsdale appeared as a mid-range trim, while the Silverado name made its first appearance as the top-of-the-line trim level. GMC, meanwhile, offered Custom and Sierra trims.

A front three-quarters shot of a beige 1985 Chevrolet K30 Crew Cab dually diesel.
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For the full-ton 30-series trucks, GM introduced the four-door crew cab configuration for the first time, which could seat six people in a 3+3 arrangement. Additionally, there was a rear seat delete option, so that the rear compartment could serve as increased storage space. There was also a double rear-wheel dually version that Chevy called the Big Dooley. GM considers this the first heavy-duty pickup truck to hit the market.

A front three-quarters shot of a red and yellow 1978 Chevrolet K5 Blazer.
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The same truck platform also underpinned the short-wheelbase Chevrolet K5 Blazer and GMC Jimmy SUVs, as well as the long-wheelbase GMC Suburban. GM marketed the third-generation C/K series concurrently with the fourth-generation GMT400 series from 1988 to 1991. To avoid confusion, the C/K square body line changed name to R/V, with the R standing for rear-wheel-drive and V for all-wheel-drive. The integrated windshield radio antenna was replaced by fender-mounted antennas.

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Chassis And Engine Options Were Aplenty

A front three-quarters static shot of a black modified 1987 Chevrolet K10 pickup.
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Compared to the previous “Action Line” generation, the wheelbase of the steel ladder frame increased by two and a half inches for better stability and a smoother ride. The rear of all models featured a two-stage leaf spring design and a live axle. There was an asymmetrical shock absorber layout, with the shock on one side of the axle slanted forward and one backward. GM claims this helped locate the rear axle during acceleration and deceleration. Rear-wheel-drive models got a fully independent double A-arm front suspension with coil springs, while all-wheel-drive variants received solid axles on both ends. The rear brakes were finned drums for better cooling, while the front was a disc brake layout with single-piston sliding calipers. Power-assisted brakes were standard and most models and available on the base C10s.

Detail shot of the 350 cubic inch (5.7-liter) engine from a 1987 Chevrolet C10.
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Several engines were available throughout the model’s long life. The entry-level inline-six came in 250- and 292 cubic-inch guises, eventually replaced by a 262 cubic-inch V-6 in the mid-80s. V-8 offerings ranged from small-block to big-block engines including 305-, 350-, 400- and 454 cubic inches. There were also a couple of diesel V-8 options: an Oldsmobile 350- and a Detroit Diesel 379 cubic-inch.

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It’s Ripe For Modification

A front three-quarters shot of a gold modified 1979 Chevrolet C10 square body.
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Classic muscle cars command insane prices these days, and thus, budget hotrodders are turning their attention to classic trucks. With its retro looks, a high number of units built, and a wide network of parts availability, the Chevy square body truck is a prime candidate for restoration or resto-modding. The simple construction makes them easy to work on, while the cavernous engine bay will swallow pretty much anything you throw in there, from a conventional LS swap to a turbo big-block setup. Detroit Speed famously offers a host of suspension upgrades to make the platform hug the road better, while a number of lift kits are available, if off-roading is more your thing. Whether you want to create a muscle truck or a 4x4 weapon, the square body Chevy offers up plenty of customization options to cater to your every need.