The body style went through a major change in 1973 and again in 1981, as was the case with this later-model example.
The cabs came in two choices: standard and crew cab. The latter had two versions: a “bonus cab” that had no rear seat and included a lockable storage compartment instead, and a “3+3” that had bench seats front and rear.
Because of these new cab and bed sizes, three wheelbases were offered for the trucks: 117½ inches for the standard-cab/short-bed pickups, 131½ for the standard-cab/long-bed trucks, and 164½ inches for the crew-cab/long-bed (or Big Dooley).
Other variants of the truck also use the same chassis, including the Custom Deluxe with camper, Blazer/Jimmy, and Suburban.
The Squarebody evolved substantially over its 14-year model run, and I’ve highlighted most of the major changes below. This will help you find the truck that best fits your needs.
1973
Compared to the previous 1967–1972 trucks, this first year of the body style had 21 percent more glass area, an optional radio antenna embedded in the glass, and a bigger cab. Front disc brakes became standard, and the entire suspension was beefed up to go along with Chevrolet’s motto, “Built to Stay Tough.” The crew cab was also introduced this year. As for the engine, this was the last year that you could buy the 307 V-8; the 402 big-block available in previous years was now replaced with the 454. There was also an inline 250- and 292-ci 6-cylinder as well as the 350-ci V-8. If you want a two-tone paint job, your second color option is white, and only white.
1974
The exterior of the truck was mostly the same, except that rain gutters became available for the areas around the side windows. Both 1973 and 1974 shared a grille commonly referred to as the recessed “egg crate” grille, named for its appearance.
1975
Higher trim levels (discussed below) came with aluminum panels on the tailgate, filling in the typically recessed area. Rain gutters were now standard on all trucks, as was a modified tailgate latch mechanism on Fleetside beds. The Scottsdale trim level was introduced. On the inside of the truck, the windshield wiper switch was modified slightly, which changed the bezels found in the 1973s and 1974s. HEI ignitions were now standard, as were catalytic converters. The front grille now featured three horizontal bars, which also eliminated the recessed feature of the previous years. This was the last year that you could find out the displacement of the engine based on the badge on the grille.
1976
Because of rust issues, General Motors added more zinc to its primer. Buyers could purchase chrome bumpers with rubber impact strips, plus they could select Rally wheels and/or a Sport model. You could now order a two-tone vehicle with a color other than white, and the Bonanza trim option was introduced. This was also the last year that the engine block was orange.
1977
Power options were available for the first time, including intermittent wipers, power windows, and power door locks. The door panels and door internal components were also different from previous years. Bucket seats came in two variations: early models had low backs and later models had high backs; it depended on when in the model year the truck was built. An inside hood release became an option and the grille changed one of the horizontal bars and four of the vertical bars were removed. A yellow/gold stripe was an option for the center of the moldings, and, other than the 1975 GMC Gentleman Jim Special Edition, this was the only year it was an option. General Motors introduced the 305 V-8, and a rear defroster also became optional.
1978
A 350 diesel engine became optional in 1/2-ton trucks. The frame was tweaked slightly to fit catalytic converters, which were now required on California trucks. This also meant that California trucks did not have a dual exhaust option available. Brushed-aluminum trim became standard on the top trim levels, replacing the wood grain. The bed received a gas door, rather than the flush gas cap found on previous years. Sometime during this model year, spade fuses were used, so glass fuses can still be found in early production units.
1979
The headlight bezels and turn signals were now combined into one unit, and General Motors added an apron underneath the grille. It also added a “decorative ridge” to the front of the hood. Trucks with a gross vehicle weight (GVW) up to 8,500 pounds now had catalytic converters as standard.
1980
The Silverado trim levels now featured rectangular headlights; other trim levels still had the round lights found in 1979. The grille gained the “egg crate” styling again (although it’s different from the 1973 version), the mirrors sat lower on the cab, and cast aluminum wheels became standard. The 292 V-6 model now had a dual exhaust option.
1981
The front end of the truck was completely changed in 1981, and it stayed essentially the same until 1987. It now had a new grille with four headlights (with two as an option) and horizontal side-marker lights. There were also new bumpers and the tailgate was also changed. The dashboard changed shape slightly, as did the seats, gauge cluster, and sill plates. The 305 V-8 now came in a California-only edition and one for the remaining 49 states. The gas tank also was relocated to the driver’s side of the truck. These changes reduced the truck’s weight by 300 pounds.
1982
The chrome grille and front bumper were now standard features. The 6.2 diesel was introduced and came with the 700R4 automatic overdrive. The 305 V-8 with the 2-barrel was discontinued. The Cheyenne trim level was discontinued.
1983
The front turn signals were relocated from the bumper to behind the grille by the headlights, and now the 700R4 automatic overdrive transmission became optional for all trucks.
1984
The quadruple headlights introduced in 1981 were now optional equipment. The wiper controls, cruise control, and high-beam lights relocated to the turn-signal stalk.
1985
This year introduced the Vor-Tex V-6 with a 4-barrel carburetor. Two-tone paint became optional again, and the grille changed slightly.
1986
This was the first year that didn’t have any major changes to the lineup. The trucks were effectively the same as in 1985.
1987
An engine equipped with throttle body injection (TBI) was introduced, and came with computerized ignition controls. This was the last year that a Stepside bed was available; the next-generation GM trucks had a “Sportside.” This was the last year of this body style, however. The 1-ton trucks, 3/4-ton trucks, Suburbans, and Blazer/Jimmys remained with few changes until 1991.
In 1973 and 1974, Chevrolet and GMC offered four trim levels for their trucks. The Custom line for both brands was considered the standard model. It was the base truck and had no option code.
The next tier was the Custom Deluxe (Chevrolet) and Super Custom (GMC), considered the mid-range truck. These had an option code of Z62.
The luxury trim was named the Cheyenne (Chevrolet) and Sierra (GMC), and had an option code of Z84.
The highest-tier luxury trucks were the Cheyenne Super (Chevrolet) and Sierra Grande (GMC). They used a YE9 option code.
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