When talking about iconic pickup trucks, the conversation will always steer towards one of the most successful lines in truck history. The longstanding Chevy and GMC C/K series that 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.

Square Body 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.

Square Body 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. 

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.

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 ship the same business day!