Jeep J20 Gladiator (Pickup Truck) Specs and Review

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Before the Wagoneer and Grand Wagoneer series rose to fame, the Jeep J20 was AMC’s primary long-wheelbase offering.

Released in 1963, the J20 succeeded the Willys Jeep 4×4 and became the American firm’s archetypal full-size truck. Ironically, it was one of Jeep’s most undervalued (not to mention misconstrued) trucks, despite having a 26-year production run.

The Jeep J20 forms part of the J-series trucks and is one of two pickups that first carried the name, Gladiator. Designed for recreation and abuse, this dual-purpose wheeler sports classic styling and spartan features and is a highly-coveted vehicle among overlanders and Jeep enthusiasts.

In all its simplicity, the Jeep J20 is one trusty ride. It is reliable as a daily driver and enjoyable as an off-roading companion.

As an overlander, the famous 1974 Jeep J20 Tomahawk build by RoamR is a perfect example of what can become of the J20 when afforded care and effort. But if you want to step up its game just a bit, a few tweaks here and there would suffice.

Interested in this classic pickup truck? Read on and discover the capabilities of this iconic 4×4.

Old Big Blue Pickup Truck 4WD

About the Jeep J20

The Jeep J20 is a full-sized pickup truck produced by then Kaiser Jeep between 1962 and 1987. Many Jeep savants consider it the firm’s quintessential truck (Willys Jeep 4×4 aside).

The J20 is one of the few Jeep vehicles that lived through three marques – from Kaiser Jeep to AMC to Chrysler. Interestingly, it also changed its label thrice – from Gladiator to J-series to J20.

Before 1974, the J20 was made available in 1/2 ton and 3/4 ton capacities and five different options, namely: cab and chassis, chassis-mounted campers with extended wheelbases, stake bed, wrecker, and load bed. The latter was split further into two bed types – Townside (wide) and Thriftside (narrow) boxes.

Designations for the J-series trucks started as a three-digit number indicating a given model’s wheelbase and GVW rating. J-2XX incarnations meant trucks with 120-inch wheelbases, while J-3XX pertained to 126-inch wheelbases.

By 1965, this format changed to four digits. And when a 132-inch wheelbase version was introduced in 1970, the J-4XXX labels were added. Eventually, J-truck designations were simplified and changed to J10, J20, and J30 in 1974.

Jeep J20 Specs & Features

Engine

Trims produced until 1966 had the option between a 3.8-L Kaiser “Tornado” I6 and a 5.3-L AMC “Vigilante” V8 mill. The next four years utilized the same engine specifications, but AMC/Buick made. In 1971, AMC offered larger-capacity engines on all versions, with the last 15 production models fitted with either 2-barrel or 4-barrel carbs.

Here are all the power mills offered during the Jeep J20’s 26-year production run, including the 221 units of ’87 Jeep trucks that carried over to 1988 (source: Jeep WikiWikipedia). Note that from the time the “J20” officially became part of the 4×4’s branding, only the 5.9-L and 6.6-L V8s were made available to consumers:

  • 1963–1966: Kaiser 3.8-L/230 cu. in. OHC I6 “Tornado”
  • 1965–1966: AMC 5.3-L/327 cu. in. V8 “Vigilante”
  • 1967–1970: AMC 3.8-L/232 cu. in. I6
  • 1967–1970: Buick 5.7-L/350 cu. in. V8 “Dauntless”
  • 1971–1973: AMC 5.0-L/304 cu. in. V8
  • 1971–1988: AMC 4.2-L/258 cu. in. I6
  • 1971–1988: AMC 5.9-L/360 cu. in. V8 with a 2-barrel carburetor
  • 1974–1988: AMC 5.9-L/360 cu. in. V8 with a 4-barrel carburetor
  • 1974–1988: AMC 6.6-L/401 cu. in. V8 with a 4-barrel carburetor

The original Tornado engine by Kaiser had an 84.8 x 111.25 mm (3.34 x 4.38 inches) bore-stroke ratio and 8.5:1 compression ratio. It also featured a six-lobe OHC design and used a cast-iron block – considered radical and quite complex by 1960s standards.

For this reason, it was discontinued in 1965 and replaced with the AMC V8 Vigilante. The latter, however, did not last long and was detuned to a 5.0-L V8 in 1971.

Nonetheless, the original mill was powerful – reportedly spewing 140 hp (103 kW) @ 4,000 RPM horsepower and a torque output of 210 Nm (21.4 kgf-m, 154.9 ft-lbf) @ 1,750 RPM.

Meanwhile, later-year 6.6-L V8s delivered 215–330 hp (158.1–242.7 kW) @ 4,200–4,600 RPM horsepower and 433–583 Nm (44.1–59.4 kgf-m, 319.4–429.9 ft-lbf) @ 2,800–3,300 RPM torque.

Powertrain

A 3-speed manual transmission was standard, while a 4-speed Tremec T-176 paired with 232 cu. in. inline-6 and 304 cu. in. V8 power mills. An optional Trac-Loc rear differential and variable-ratio power steering improved traction and compensated for the absence of the Quadra-Trac system found only in auto-transmission packages.

Add-ons aside, the base model still performed satisfactorily and boasted impressive handling mannerisms characteristic of passenger vehicles.

  • 1963: Warner AS-8F 3-speed automatic
  • Warner T-90 3-speed manual (4WD, up to 5,600 GVW)
  • Warner T-89 3-speed manual (2WD/4WD, more than 5,600 GVW)
  • Warner T-98A 4-speed manual (6.32 1st gear)
  • Warner T18 4-speed manual
  • Warner T18A 4-speed manual (6.32 1st gear)
  • Tremec T-176 4-speed, used with AMC 3.8-L I6 and 5.0-L V8 engines
  • 1964–1979: AMC 3-speed GM THM400 automatic
  • 1980–1988: 3-speed Chrysler A727 Torqueflite automatic

All automatic transmissions are with Quadra-Trac Hi-Range. Inclusion of Lo-Range is optional and costs more than the extra $153–$591 drivers needed to add to the base package rate in the late ’70s (source: Popular Mechanics archive issue).

As for rear axles, 1/2 ton trims were fitted with “closed-knuckle” Dana 44, while 3/4 ton versions had Dana 60. In 1983, the full-time 4WD Selec-Trac replaced the optional Quadra-Trac system.

Brown 1974 Jeep J20 Pickup

Tires, Brakes & Suspension

Jeep J20 parts, like stock tire sizes, largely depend on the year and trim of the truck. An ’83 model with a 6,800 GVWR, for instance, would fit an 8.75 x 16.5 set of 6-ply radial tires, while a similar model with a 7,600 GVWR would require wider 9.50 rims. Meanwhile, an ’88 model would fit a 9.50 x 16.5 set of tires but with an 8-ply rating.

Furthermore, these pickup trucks initially had independent front suspension, which was quite different from the usual solid front axle found on most full-sized trucks at the time. The setup employed a Dana 44 center section that became problematic and was eventually discarded in 1965.

On the other hand, its braking system was reliable and consisted of 12.5-inch power discs.

Dimensions

Overall dimensions are 206 x 78.9 x 70.7 inches (5,232.4 x 2,004 x 1,795.8 mm – L x W x H). Cargo bed dimensions are 2,428.2 x 1,727.2 mm (95.6 x 68 inches – L x W), with a tailgate loading height of 28.3 inches (718.8 mm) and a 38.6–44.4 cu. ft. bed capacity.

Front tread is 63.9–64.6 inches (1,623–1,640.8 mm), and rear tread is 63.8–64.4 inches (1,620–1,635.7 mm, 1972 model). Depending on trim, wheelbase size went from 120 inches (3.048 mm) to 165 inches (4,191 mm).

Similarly, GVWR (Gross Vehicle Weight Rating) ranged from 4,000 lbs. (1,814.4 Kg) to 8,600 lbs. (3,900.9 Kg).

Exterior

Cosmetic alterations made on the Jeep J20 trucks were inadequate in count and effect. It was not until 1973 that changes made became noticeable. These included double-wall side panels in the cargo area, a single-hand-operated, wider tailgate, and a redesigned instrument panel with more visible and larger gauges.

Furthermore, the J20 received larger brakes in 1974 and an upgraded frame and improved windshield washer in 1976.

The Jeep J20 had a quad-lamp front end until 1969 that was changed to a full-width razor grille with signature round headlights the following year. Square headlamps replaced the circular ones in 1979 but were ditched for the trademark lights later on.

The razor grille, in particular, remained unchanged until 1978. The Jeep truck series was also known for its roof lip, which remained part of its aesthetic until 1981.

Two-tone and non-standard paint colors were available for an additional $24–$61. However, some of the below options were not available with specific packages, like the Honcho and Golden Eagle:

  • Alpine White
  • Autumn Red Metallic
  • Brilliant Blue
  • Classic Black
  • Firecracker Red
  • Golden Ginger Metallic
  • Loden Green Metallic
  • Mocha Brown Metallic
  • Oakleaf Brown
  • Pewter Gray Metallic
  • Sand Tan
  • Sun Orange
  • Sunshine Yellow

Nowadays, Jeep J20s are increasingly becoming popular as an overlander. If this is your intended application for the vehicle, I highly recommend getting a front-runner roof rack, 35- to 40-inch tires, high-clearance snorkels, and a swing-out tire carrier that can also hold your Hi-Lift jack (view on Amazon). I would also suggest conversion to an Alu-Cab for full-time campers.

A Shift Pod tent or Gazelle T4 works great for solo travels or group camping (up to three people and a pet can fit inside the latter). In colder regions, a quilted Eskimo QuickFish Series Pop-Up Portable Ice Fishing Shelter (view on Amazon) may be a more viable option. It has a more spacious 10′ x 10′ area and a chimney hole to boot.

Standout Packages

Unlike other Jeep labels, the Jeep J20 only offered two trims – these do not include the Honcho, and Laredo trims, which many believed were part of the 4×4’s special packages. In this section, let us briefly go over these two offerings:

Pioneer:

This package was available for the Jeep J20 beginning in 1974 and lasted until the vehicle’s outgoing year. Its first two years featured a woodgrain trim on the exterior, woodgrain door panels, and an instrument cluster similar to the Jeep Wagoneer. But its most distinctive décor is a “Pioneer” emblem under the J20 badge.

Golden Eagle:

Not exclusive to the Jeep J10, this trim was originally marketed from 1977 to 1983. It was shared by several Jeep labels such as the Renegade, Scrambler, and even the Wrangler. On all these models (including the J20), an extravagant golden eagle decal is seen sprawled on the vehicle’s hood.

Other features of this package are spoked steel rims, body striping, a chrome front bumper, and wheel lip extensions.

Jeep J20 Price

The MSRP of the 1963 Jeep Gladiator J20 was between $1,913 and $3,073 (worth roughly $17,973 – $28,870 if sold brand-new today and with inflation factored in). The full-sized pickup was then still marketed as the Jeep Gladiator and was best known for its Townside (wide) and Thriftside (narrow) boxes.

The vehicle did not officially carry the “J20” branding until 1974, when AMC decided to simplify the designation of its product offerings.

Despite a drop in its MSRP in its 3rd production year, the J-series saw incremental price changes. Since Kaiser took over the company, there would always be a $200 – $300 difference between 4×2 and 4×4 trims, regardless of payload capacity.

The J-20 lineup was able to keep its price tag under $5,000 until 1977. Soon after, it increased by as much as $4,000 for some of its iterations.

1963–1988 Jeep Gladiator, J-Series

Year – Trim – Model NumberList PriceRetail/Trade-In Values
1963 Jeep Gladiator (Base)$1,913N/A
1963–1964 Jeep Gladiator Townside (1/2 Ton)$2,722 – $2,806$5,125 – $25,600
1963–1964 Jeep Gladiator Townside (1/2 Ton, 4×4)$2,796 – $2,881$5,550 – $26,900
1963–1964 Jeep Gladiator Townside (3/4 Ton)$2,881 – $2,886$5,000 – $25,300
1963–1964 Jeep Gladiator Townside (3/4 Ton, 4×4)$3,073 – $3,166$5,175 – $25,800
1963–1964 Jeep Gladiator Thriftside (1/2 Ton)$2,696 – $2,779$5,300 – $26,900
1963–1964 Jeep Gladiator Thriftside (1/2 Ton, 4×4)$2,769 – N/A$5,300 – $26,700
1963–1964 Jeep Gladiator Thriftside (3/4 Ton)$2,854 – $2,942$5,175 – $25,800
1963–1964 Jeep Gladiator Thriftside (3/4 Ton, 4×4)$3,046 – $3,139$5,675 – $27,100
1965–1969 Jeep Gladiator Townside (1/2 Ton)$2,423 – $3,661$5,300 – $26,500
1965–1969 Jeep Gladiator Townside (1/2 Ton, 4×4)$3,083 – $3,497$5,700 – $27,600
1965–1969 Jeep Gladiator Townside (3/4 Ton)$2,582 – $3,410$5,200 – $25,600
1965–1969 Jeep Gladiator Townside (3/4 Ton, 4×4)$3,247 – $3,695$5,550 – $26,900
1965–1969 Jeep Gladiator Thriftside (1/2 Ton)$2,396 – $3,348$5,700 – $27,100
1965–1969 Jeep Gladiator Thriftside (1/2 Ton, 4×4)$3,056 – $3,469$5,675 – $27,100
1965–1969 Jeep Gladiator Thriftside (3/4 Ton)$2,555 – $3,343$5,550 – $26,900
1965–1969 Jeep Gladiator Thriftside (3/4 Ton, 4×4)$3,247 – $3,633$5,850 – $29,100
1970–1973 Jeep Thriftside (1/2 Ton, 4×4)$3,406– $3,610$4,750 – $21,700
1970–1974 Jeep J20 Townside (3/4 Ton, 4×4)$3,804 – $4,375$4,575 – $21,300
1975–1978 Jeep Townside (3/4 Ton, LWB, 4×4)$ 4,925 – $6,324$4,750 – $19,500
1970–1979 Jeep Townside (1/2 Ton, 4×4)$3,474 – $6,172$4,750 – $23,000
1974–1979 Jeep Townside (1/2 Ton, LWB, 4×4)$3,834 – $6,872$5,000 – $22,700
1979 Jeep J20 Townside (3/4 Ton, 4×4)$6,245$4,575 – $18,000
1980–1984 Jeep J20, Townside (3/4 Ton, LWB, 4×4)$7,837 – $11,043$4,800 – $19,300
1985–1988 Jeep J20, Townside Pickup (3/4 Ton, 4×4)$11,275 – $13,525$5,550 – $20,700
(Source: Nada Guides)

Difference Between the Jeep J10 and J20 (Part II)

In my previous article on the Jeep J10, I cited notable differences between the two J-series pickup trucks. However, most of what I covered has to do with vehicle specs and GVWR (Gross Vehicle Weight Rating).

Since the Jeep J20 looks oddly similar to the former, I opted to list down some tips (plus other attributes) that would make it easier to tell them apart, if not help you decide on the better vehicle:

  • J10s also have long-bed versions like the Jeep J20, so do not differentiate them based on dimensions and appearance alone.
  • Between the two, J20s have better axles, given their higher GVW rating.
  • Go for post-1976 models if you are in search of a J-truck with a stronger frame.
  • The higher the GVWR of your J20, the rougher the ride quality will be due to spring weight.
  • Modification-wise, Jeep J20s would be better suited for tire sizes over 36 inches. Anything smaller than that, and you are better off with a J10.
  • If you reside in California, look for secondhand J20s manufactured during the smog-exempt years (1975 or earlier).
1979 AMC Jeep J20 Pickup

About Stellantis

Stellantis N.V. is a multinational manufacturing firm responsible for giving birth to classic pickup trucks like the Jeep J20. It has a long history – tracing its humble beginnings to American firm Willys–Overland Motors, founded in 1908, and Peugeot, founded in 1810.

The discovery of their respective specialties, expansion of their product offerings and market reach, and a series of mergers from both parties led to the current industry giant that is Stellantis.

Conclusion – J20 Jeep Review

The Jeep J20 is undeniably the embodiment of “old American iron.” Moreover, it is a dependable dual-purpose vehicle and a promising build project. Interchangeable parts with Cherokee and Wagoneer models form part of its appeal as a viable secondhand purchase.

However, do not underestimate restoration/repair costs, as the wheeler can easily turn into a money pit if thorough and careful planning is not exercised.

Before buying a pre-owned J20, ascertain the vehicle’s application and go from there. Are you going to use it as a workhorse or your daily driver? Or do you intend to take it overlanding? This classic wheeler can do them all. So whichever you decide, equip your J20 accordingly and enjoy the ride!

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