The D21 generation was the successor to the Datsun "720". The company used the name "Datsun" from 1980-1981 then renamed itself "Nissan" beginning with the 1982 model year line of trucks and cars alike. Nonetheless, the Nissan pickups continued to be marketed in the Japanese home market as the "Nissan Datsun". The D21 series were unofficially called Nissan Hardbody in the United States.

The truck's name, "Hardbody", refers to its double-wall bed and overall styling. The Hardbody was produced for the U.S. Market from 1986.5 until 1997, and were direct competition to the Toyota compact pickup. The move from the 720 to the D21 Nissan series body style changed mid-year 1986.5 so the new 'D21' 1986.5 and later Hardbody can easily be distinguished from the earlier 720 body style by its two large headlights rather than four smaller lights and a less boxy, more aggressive appearance. The Nissan Pathfinder was derived from the Hardbody Truck and started in the same model year with chassis code WD21.  dIn the US, the Hardbody cab styles were 'Standard' and 'King' (also known as 'Extended'). Bed lengths were 'standard' 6-foot (2 m) and 'long' seven foot. International markets also received the 'Crew Cab' (4-door) version with a short four and a half foot bed.

4-cylinder and V6 engines were available, with the 2.4L 4-cylinder KA24E being a respectable-performance SOHC engine that replaced the Z24i for 1990–1997 with a new 3-valve-per-cylinder head. The 6-cylinder 3.0L VG30i (early years) or VG30E (later years) engine increased power and torque only modestly and was unavailable in the US starting with the 1996 model year because Nissan was unable to meet in time the requirements of the new OBD-II emissions law.

Five-speed, including overdrive, manual transmissions were the most common, but an automatic transmission was an available option. Both rear-wheel-drive (4x2) and four-wheel-drive (4x4) versions were made in quantity. A limited slip differential was standard on the top 'SE' trim 4WD variants.

Major options included air conditioning, larger wheels/tires, sliding rear window, stereo, and rear bumper. There were several trims available including base, XE, and top of the line SE. The XE could be ordered with a 'value package' starting in 1994 which included air conditioning, power mirrors, alloy wheels, and chrome on body trim such as the mirrors and bumpers. The SE was better equipped and could be ordered with the "sport power package" with sunroof, power windows, locks, and mirrors, air conditioning and special "Robot" alloy wheels.

In 1993, Nissan had a strange model year crossover which had the dashboard of the 1986.5–1992 model years with a slightly refreshed body appearance as well as some small interior changes and a revised instrument panel. In a first for the auto industry, this model used the new R134A air conditioning refrigerant.

1994 would be the last major refresh through 1997. A new ergonomic dashboard and much improved interior arrived.

1995 was the first model to comply with the new US, Department of Transportation "high mount brake light" regulation requiring all trucks to have a brake light in the center of the rear at the top of the cab.

In 1996, a driver's side airbag was added as well as compliance with the new US OBD-II emissions law. Rear wheel ABS came with both 2WD and 4WD models beginning in 1991.

Versions sold in other countries came with a host of more economical engines, ranging from 1.6-litre gasoline fours up to a 2.7-litre diesel four-cylinder, including SD25 and TD25 diesel engines.

Full Bosch four-sensor (all-wheel) ABS would not be available until the "new" 1998 D22 series, "Frontier" pickups were released to the public.

These low-cost, dependable Hardbody small pickup trucks sold very well worldwide, and are still often seen both on-road and off-road. They are renowned for their reliability and endurance, with the exception of body panel and frame rust over time. Other things to look for are a noisy timing chain on the 1990–1997 KA24E (2.4) 4cyl engine in particular which had a problem with the stock timing chain guides and slippers deteriorating, breaking off and allowing the timing chain to damage the timing cover, seizing the chain to the engine and/or timing cover, as well as damaging pistons and bending valves requiring serious engine work in extreme cases. This was remedied by buying aftermarket engine timing parts, (particularly the chain guide, slipper and tensioner), and repairing immediately when noises became apparent. Otherwise, the KA24E was an excellent engine. The V6 engine had a timing belt that requires replacing every 60K miles. Exhaust manifold studs were well known to fail prematurely due to heat embrittlement from poor materials quality, on all years from 1986.5- 1995. In the US, beginning in 1998, the new "D22" was officially named, "Frontier" and used a new DOHC 2.4 4cyl borrowed from the Nissan Altima. A newly modified "VG33" V6 was available in 1999 and ending production in the US in 2004. The new VG33E V6 had new, larger, 10 mm exhaust manifold studs in an attempt to decrease the risk of premature exhaust manifold stud failure, but still had limited success. The truck was used by Jeremy Clarkson on Top Gear for crossing the English Channel in 2007 with an outboard motor attached to the back.

In general however, the VG30E and VG33E V6's were both amazingly reliable engines.

The D22 is still being made in South Africa and elsewhere in the world.

The D21 design was still available new in some Latin American countries, made in Mexico until the 2008 model year. In its current home country a range of four basic variations of the D21 are sold together as the Nissan Camiones (literally "Nissan Trucks").

End of production

Nissan Mexicana ended production of the Camiones on March 15, 2008 after 15 years of production in the Cuernavaca plant.