Chevrolet K10 Square Body: History, 4x4 Specs, and Spotting Guide

The Square Body Takes Over

Chevrolet's third-generation C/K trucks debuted for the 1973 model year, replacing the rounder, chrome-heavy Action Line generation that came before. The new trucks traded curves for flat glass and creased sheet metal, a look owners and, eventually, the whole hobby started calling "square body." The K10 badge marked the half-ton 4x4 version of the truck, the C10's four-wheel-drive sibling, riding higher on a solid front axle and built for exactly the kind of unplowed mountain road and muddy farm lane these renders put it on. The square body's basic shape proved durable enough that Chevrolet and GMC kept building it, essentially unchanged at a glance, all the way to 1987. The same platform underpinned the K5 Blazer, Chevrolet's full-size SUV, which used a shortened version of the K10's frame and shared its front sheet metal and running gear through most of the square body years.

Engines: Sixes, Small-Blocks, and GM's First Diesel

The K10 launched with a familiar GM lineup: 250 and 292 cubic-inch inline-sixes, and 307 and 350 cubic-inch V8s. A 305 cubic-inch V8 joined the half-ton options in 1977, slotting a smaller small-block between the six and the 350. Then, in 1978, GM did something new: it offered an Oldsmobile-built 350 cubic-inch diesel V8 (RPO code LF9) in its C/K pickups, among the first diesel engines offered in an American full-size pickup (Dodge introduced a Mitsubishi-built diesel option of its own that same year). The Olds diesel earned a rough reputation for reliability, and GM replaced it in 1982 with its own 6.2-liter Detroit Diesel V8, a sturdier design that stayed in GM trucks for years afterward. On the gas side, the long-running 250 inline-six was finally retired in 1985, replaced by a 4.3-liter (262 cubic-inch) V6. Transmissions ran the same broad range: three- and four-speed manuals, including the heavy-duty SM465 and the New Process NP833, backed up by Turbo Hydra-Matic 350 and 400 three-speed automatics, with an overdrive-equipped 700R4 automatic arriving in 1982 to help the bigger diesel and gas V8s cruise at lower RPM on the highway.

Custom Deluxe, Scottsdale, Silverado: The Trim Ladder

Square body trim names shifted more than once. For 1973-74, the lineup ran Custom, Custom Deluxe, Cheyenne, and Cheyenne Super, with Cheyenne Super as the loaded option. Chevrolet restructured the ladder for 1975: Custom Deluxe became the base trim, Scottsdale slotted in as a mid-level package, and Silverado arrived at the top, replacing Cheyenne Super as the truck's plushest offering, a name Chevrolet liked well enough to keep using on its full-size trucks long after the square body was gone. Buyers who wanted extra capability without stepping up to an actual three-quarter-ton could also order the Big 10, or Heavy Half, a package of heavier-duty springs and brakes that pushed the half-ton's gross vehicle weight rating just over 6,000 pounds, the threshold that exempted it from the stricter emissions equipment required on lighter trucks.

Round Lights, Square Lights: Dating a K10 by Its Face

Because the square body ran so long without a full redesign, headlights are the quickest way to bracket a truck's age. From 1973 through the late 1970s, K10s ran dual round headlights in a simple chrome-trimmed grille. Around 1980, a square-headlight front end began appearing on some higher trims, alongside a flatter grille, before the real changeover arrived with the 1981 facelift, when square headlights became standard across the range: base trucks got a single rectangular light per side, while upper trims like the Silverado ran four smaller lights stacked in pairs. A render or a real truck showing round headlights points to the 1973-79 era; square or stacked-quad lights point to 1981 and later, with 1980 as a rare in-between year worth checking closely rather than assuming.

From R/V Back to a New Generation

The square body's long run ended, on paper, in 1987. That April, Chevrolet introduced its all-new GMT400-platform C/K trucks for the 1988 model year, and to keep the two generations straight on dealer lots, GM redesignated the outgoing square body line as R/V. The R/V name wasn't just a badge change on regular pickups, either; it carried on through 1991, mostly on the Suburban, the Blazer and Jimmy SUVs, and heavy-duty crew-cab trucks the new GMT400 line hadn't replaced yet. For the K10 half-ton pickup specifically, though, 1987 marked the end of the square body shape most people picture when they hear the name.