Classic trucks only continue to grow in popularity, and the third-generation Chevrolet and GMC C/K trucks are no exception. Produced from 1973 until 1987, the style of these particular pickups is commonly referred to as the box body or square body Chevy. Formally dubbed the “Rounded-Line” generation, this was one of the longest-running generations of pickups produced by Chevy. Since they were in production for a 14-year period, they are less rare than other classic Chevy trucks, such as the 1967-1972 Action Line or “Glamour Pickups” that were only available for a few short years. Because they are easily accessible and affordable, restoring box body Chevys has become popular in the decades since their initial release.
As with most automotive generations, there were several changes that occurred throughout the third generation of C/K trucks. In order to help you tell the difference between certain years, CJ’s has put together a Square Body Chevy Identification Guide.
[click the graphic below]
Sporting a completely different look from the previous generation, Chevy took the design in another direction for the third-generation C/K pickups. Available trim levels include the Cheyenne, Cheyenne Super, Custom, and Custom Deluxe. With a wider and larger frame, the trucks were coined the square body Chevys as they had a box-like appearance. Early third-generation models from 1973-1980 had a different hood style than the later models. Wheelbase for both the 6.5-foot box and 8-foot bed increased, bringing the short wheelbase up 2.5 inches to 117.5 inches and the long wheelbase up 4.5 inches to 131.5 inches. Along with the addition of a front stabilizer bar, front spring rates were reduced and rear shock absorbers were staggered to prevent wheel hop. Rather than circular wheel wells, the trucks featured a squarer wheel opening with rounded corners. Rounded door frames and windshields contrast the square body design for a balanced look. Vision was increased with over 20% more glass area, greatly decreasing blind spots. Sculpted sides gave the trucks added dimension. In 1973, Chevy also began offering the C30 one-ton dually with a Crew Cab, largely considered to be one of the first modern heavy-duty pickups. The 307 V8 engine was dropped in 1973 and the 402 was replaced by the more powerful 454. Rain gutters above the door became available in 1974. When the NP203 transfer case became available for models with the V8 engine, it was equipped with full-time four-wheel drive. The recessed egg-crate grille is only available for the 1973-1974 model years. This new generation brought drastic visual changes compared to the previous model year 1972 Chevy C10, which may appeal to enthusiasts who want a more "classic Americana" look with more rounded lines.
Starting in 1975, Chevy revised the trim level offerings and began offering the luxury Silverado trim that eventually replaced the C/K in 1999. The Silverado took over from the Cheyenne Super as the top trim level. The Custom Deluxe became the base model as the Custom line was dropped, and the Scottsdale edition became available. The 1975 Chevy trucks were a hot product, with almost 750,000 vehicles sold that year. The windshield wiper switch moved to a different location than the previous third-generation C/K models and no longer had back lighting. A quick-release tailgate became standard for the Fleetside models and rain gutters were standardized across all models. Catalytic converters became standard in 1975 for all trucks with a gross vehicle weight rating under 6,001 pounds. The major difference when it comes to appearance is the grille change. From 1975-1976, the grille features three horizontal bars and sits flush with the front. The engine size badge on the grille was removed beginning in 1976.
The Silverado, Cheyenne, Custom Deluxe, and Scottsdale were the available trim models for 1977-1979. Another new grille design entered the scene for these model years. With fewer vertical dividers and one less horizontal divider, it’s easy to differentiate these grilles from the rest. An inside hood release was also an available feature. Additional hood details were also added in 1979, along with power windows. Low-back bucket seats could be found in early 1977 pickups, while high-back bucket seats were used in later models. A 5.7L V8 diesel engine became available in 1978, only for the Chevy C10. The flush-mounted gas cap was replaced by a new fuel filler door. There were over 1,300,000 trucks sold in 1978, which was a record-breaking figure. Starting in 1979, the headlight bezels incorporated the front turn signals, while the previous grille designs had featured separate headlight and turn signal housings. The same year, catalytic converters were standardized on all trucks with a gross vehicle weight rating up to 8,500 pounds.
As the outlier of the group, the 1980 square body Chevy features a unique egg-crate grille that was only made for one year. Other than that, the body style pretty much stayed the same except for more chrome across the bottom of the grille and optional rectangular headlamps, which were standard for the Silverado and Sport trims. Thanks to user “80Sport” on 67-72chevytrucks.com for posting this photo of a 1980 Chevy truck!
A mid-generation refresh took place in 1981, with Chevy introducing a new front end with redesigned sheet metal. Along with the changes came a 300-pound weight reduction. The same front sheet metal was used throughout the rest of the third generation until 1987. The fenders were redesigned as well as the hood hinges and vent windows. A new sloped hood replaced the previous hood that had less rake, and the bumper had less detailing than before. Exterior changes include optional quadruple headlights, new bumpers, and an updated tailgate. Side markers were now horizontal rather than vertical. The windshield wipers moved from behind the hood to the top of the cowl. The inside of the trucks also received a refresh with a new instrument panel, seats, dash shape, and sill plates. In 1982, a chrome grille and bumper became standard on all trucks. A 6.3L 379 diesel became available with a 4-speed overdrive manual transmission. Trim levels consisted of the Custom Deluxe, Silverado, and Scottsdale, with the Cheyenne discontinuing. Thanks to user “The Champ” on 67-72chevytrucks.com for sharing this photo of a 1981 C10 Scottsdale edition!
For 1983 and 1984, the square body Chevy featured a two-level grille, and the turn signals changed locations from the bumper to behind the grille. In addition to the grille change, there were a few updates to the trim on both the interior and exterior.
Yet another redesign of the grille took place in 1985 and lasted until the Rounded Line generation finally came to a close. During this time, the 4.3L Vortec V6 engine with fuel injection technology became the most powerful base engine for Chevy trucks. Beginning in 1987, the C/K trucks underwent a new naming designation. Model names were switched from 10, 20, and 30 to 1500, 2500, and 3500, respectively. The square body C10 came to an end as well as the C10 generation as a whole. The C1500 went on to become the Silverado, which remains Chevrolet’s most popular truck to this day.
Sources: 73-87.com, Auto Restorer Magazine, trucktrend.com, fourwheeler.com, Truckin’ Magazine | Image Credit: hotrod.com, gmheritagecenter.com, chevytrucklegends.com, media.chevrolet.com, autowise.com, trucktrend.com, barnfinds.com, 67-72chevytrucks.com
Back To Top