# Chrysler B platform
The Chrysler B platform, known in [Mopar](https://www.edgepedia.org/mopar) circles as the B-body, was a rear-wheel-drive, unibody automobile platform used by Chrysler Corporation for its mid-size cars from the 1962 through 1979 model years. It underpinned many of the company's best-known vehicles, including the [Dodge Charger](https://www.edgepedia.org/dodge-charger), Plymouth Road Runner, Plymouth GTX, Plymouth Satellite, and [Chrysler Cordoba](https://www.edgepedia.org/chrysler-cordoba).[1](https://laukkanenmotorsport.fi/en/a38/mopar-master-platform-reference-table)
| Key fact | Detail |
|---|---|
| Production span | 1962–1979 model years[1](https://laukkanenmotorsport.fi/en/a38/mopar-master-platform-reference-table) |
| Layout | Rear-wheel drive, unibody construction with torsion-bar front suspension[2](https://www.hotrod.com/features/plymouth-muscle-cars) |
| Origin | 1962 downsizing of Dodge and Plymouth from a planned 119-inch wheelbase to 116 inches[3](https://www.1962to1965mopar.ornocar.com/62exner.html) |
| Chassis design | Upscaled version of the Valiant's K-member unibody, with wider K-members to fit big-block V8s[4](https://macsmotorcitygarage.com/the-origins-of-chryslers-famous-b-body-platform-1962-79/) |
| Nameplate users | Coronet, Charger, Road Runner, GTX, Satellite, Belvedere, Fury, Cordoba, Magnum[1](https://laukkanenmotorsport.fi/en/a38/mopar-master-platform-reference-table) |
| Final cars | 1978–1979 Dodge Magnum and 1979 Chrysler Cordoba, though some sources classify the 1979 cars as R-body[5](https://www.dodge-wiki.com/wiki/Dodge_Magnum) • [6](https://journal.classiccars.com/2023/11/07/pick-of-the-day-1979-dodge-magnum-xe-2/) |
## Origins in the 1962 downsizing
The B-body began as a rushed corporate decision. Chrysler executive Bill Newberg, convinced that [Chevrolet](https://www.edgepedia.org/chevrolet) was going to downsize its full-sized Impala for 1962, ordered the shrinking of the 1962 Dodge and Plymouth from their planned 119-inch wheelbase to a new 116-inch chassis. The rumor was false; Chevrolet kept the Impala full-sized and added the smaller Chevy II. The crash redesign produced cars that Chrysler's design chief [Virgil Exner](https://www.edgepedia.org/virgil-exner) called "plucked chickens," and when the downsized Dodges and Plymouths failed in the marketplace, Exner was called into Chrysler president Lynn Townsend's office in the fall of 1961 and fired.[3](https://www.1962to1965mopar.ornocar.com/62exner.html)
The 1962 Plymouth was 7.5 inches shorter, 4.5 inches narrower, and roughly 350 pounds lighter than an equivalent model from the previous year.[7](https://www.indieauto.org/2021/01/02/did-a-rumor-cause-the-downsized-1962-plymouth-and-dodge/) Sales of the 1962 models were poor, but the 1963 and 1964 Plymouths, given more conventional styling, outsold the standard-sized 1960 and 1961 models.[7](https://www.indieauto.org/2021/01/02/did-a-rumor-cause-the-downsized-1962-plymouth-and-dodge/)
## Chassis engineering
The platform's underpinnings came from Chrysler's compact. For the Valiant introduced in 1960, Chrysler engineers devised a unibody with a single stamped and welded crossmember, the K-member, which carried all engine and lower suspension mountings and fastened to the frame runners with four 5/8-inch machine screws. Because the 1962 downsizing left no time to develop a new chassis, Chrysler upscaled this Valiant K-member unibody system for the bigger cars. The designs are essentially the same, including an identical four-point mounting pattern for the K-member; on the B-body the frame runners sit a few inches farther apart to accommodate big-block V8s, so the K-members are wider as well.[4](https://macsmotorcitygarage.com/the-origins-of-chryslers-famous-b-body-platform-1962-79/)
The platform acquired the name B-body at Chrysler in 1964.[4](https://macsmotorcitygarage.com/the-origins-of-chryslers-famous-b-body-platform-1962-79/) Despite its compact-derived structure, the B-body was closer in size and weight to the 1961 big Plymouth than to the Valiant: the B-body Plymouth was longer than the Valiant by 15.8 inches and wider by 5.2 inches, with front track and hip room wider by 3.5 inches and 4 inches respectively, and it weighed only 350 pounds less than the 1961 full-sized Plymouth. Widening the passenger cabin required a new cowl and windshield, so the B-body was not a stretched compact in any literal sense.[8](https://www.indieauto.org/2024/10/08/a-deeper-dive-into-why-chryslers-1962-b-body-wasnt-a-stretched-compact/)
## Models and role in the lineup
In 1965 Chrysler introduced a new, larger full-size [Plymouth Fury](https://www.edgepedia.org/plymouth-fury) on the C platform, and the Belvedere name moved to Plymouth's mid-size line, which was in reality a continuation of the 1962–1964 full-size B-body cars. The [Plymouth Satellite](https://www.edgepedia.org/plymouth-satellite), introduced in 1965 as the top model of the Belvedere line, remained on the B platform through 1974; the Fury name moved to Plymouth's mid-size models for 1975, and the B-body chassis continued as the Plymouth Fury through 1978.[9](https://www.dodge-wiki.com/wiki/Plymouth_Satellite)
The B-body became the foundation of Chrysler's muscle-car era. The Plymouth B-body intermediates of 1962–1967, including the Savoy, Belvedere, and Fury, combined slim yet robust unibody construction with engines such as the 383-cubic-inch Wedge big-block, the 413- and 426-cubic-inch Max Wedge versions, and eventually the 426 Street Hemi.[2](https://www.hotrod.com/features/plymouth-muscle-cars) Later B-body models included the Dodge Charger (1966–1978), [Dodge Coronet](https://www.edgepedia.org/dodge-coronet) (1965–1976), [Plymouth Road Runner](https://www.edgepedia.org/plymouth-road-runner), Plymouth GTX, and, in its final years, the Chrysler Cordoba (1975–1979) and [Dodge Magnum](https://www.edgepedia.org/dodge-magnum) (1978–1979).[1](https://laukkanenmotorsport.fi/en/a38/mopar-master-platform-reference-table) • [10](https://www.jegs.com/tech-articles/?p=3542)
## NASCAR and the aero warriors
The platform reached its most visible form in stock car racing. The 1969 [Dodge Charger Daytona](https://www.edgepedia.org/dodge-charger-daytona) was a Charger B-body re-engineered around an 18-inch pointed steel nose cone, flush A-pillar plugs, a flush rear backlight, and a towering rear-mounted horizontal wing, built to legalize the aero package for NASCAR superspeedway competition. On 24 March 1970, Buddy Baker drove a Chrysler engineering Daytona at Talladega to the first lap of a closed circuit at more than 200 mph in NASCAR history. The [Plymouth Superbird](https://www.edgepedia.org/plymouth-superbird) followed for 1970 on the Road Runner shell, and NASCAR then legislated the aero cars out of competition.[11](https://www.carcollectorinternational.com/research/buyers-guides/dodge/charger-daytona)
## End of the platform
The 1978 and 1979 Dodge Magnum, assembled in [Windsor, Ontario](https://www.edgepedia.org/windsor-ontario), on a 115.0-inch wheelbase, was described by Dodge references as the last vehicle to use the long-running Chrysler B platform; it replaced the Charger SE and allowed [Richard Petty](https://www.edgepedia.org/richard-petty) to continue racing with a Mopar.[5](https://www.dodge-wiki.com/wiki/Dodge_Magnum) Sources disagree on the final cars' designation: ClassicCars.com states that the 1979 Cordoba and Magnum are R-body cars rather than B-body, while other references and enthusiast sources count them as the last B-bodies, succeeded by the 1980 Dodge Mirada on the new J-body platform.[6](https://journal.classiccars.com/2023/11/07/pick-of-the-day-1979-dodge-magnum-xe-2/) • [5](https://www.dodge-wiki.com/wiki/Dodge_Magnum) A Department of Transportation industry report records that the Fury and Monaco B-bodies served as Chrysler's interim standard-sized cars pending the introduction of the new R-body in 1979.[12](https://rosap.ntl.bts.gov/view/dot/10482/dot_10482_DS1.pdf)
The platform's 18-year run left a lasting parts and restoration ecosystem. Mopar's licensed restoration suppliers cover exterior sheet metal, bumpers, glass, floor pans, and related hardware for B, E, and A body vehicles from 1966 to 1974, and B-body K-members are widely interchangeable across model years, which facilitates engine swaps and other modifications.[13](https://www.mopar.com/en-us/shop/parts/mopar-restoration-parts.html) • [4](https://macsmotorcitygarage.com/the-origins-of-chryslers-famous-b-body-platform-1962-79/)
## References
1. [Mopar Master Platform Reference Table, Laukkanen Motorsport](https://laukkanenmotorsport.fi/en/a38/mopar-master-platform-reference-table)
2. [Plymouth Muscle Cars You Need to Know, Hot Rod](https://www.hotrod.com/features/plymouth-muscle-cars)
3. [The 1962 Plymouth Dumbsizing (excerpt from Godshall, Collectible Automobile, October 1992), 1962to1965mopar](https://www.1962to1965mopar.ornocar.com/62exner.html)
4. [The Origins of Chrysler's Famous B-Body Platform, 1962-79, Mac's Motor City Garage](https://macsmotorcitygarage.com/the-origins-of-chryslers-famous-b-body-platform-1962-79/)
5. [Dodge Magnum, Dodge Wiki](https://www.dodge-wiki.com/wiki/Dodge_Magnum)
6. [Pick of the Day: 1979 Dodge Magnum XE, ClassicCars.com Journal](https://journal.classiccars.com/2023/11/07/pick-of-the-day-1979-dodge-magnum-xe-2/)
7. [Did a rumor cause the downsized 1962 Plymouth and Dodge?, Indie Auto](https://www.indieauto.org/2021/01/02/did-a-rumor-cause-the-downsized-1962-plymouth-and-dodge/)
8. [A deeper dive into why Chrysler's 1962 B-body wasn't a stretched compact, Indie Auto](https://www.indieauto.org/2024/10/08/a-deeper-dive-into-why-chryslers-1962-b-body-wasnt-a-stretched-compact/)
9. [Plymouth Satellite, Dodge Wiki](https://www.dodge-wiki.com/wiki/Plymouth_Satellite)
10. [Mopar Body Types: A Complete Guide, JEGS](https://www.jegs.com/tech-articles/?p=3542)
11. [Dodge Charger Daytona Buyer's Guide (1969–1970), Car Collector International](https://www.carcollectorinternational.com/research/buyers-guides/dodge/charger-daytona)
12. [LUXUR passenger car report, U.S. Department of Transportation (ROSAP)](https://rosap.ntl.bts.gov/view/dot/10482/dot_10482_DS1.pdf)
13. [Authentic Restoration Parts, Official Mopar Site](https://www.mopar.com/en-us/shop/parts/mopar-restoration-parts.html)
---
*Topic: Encyclopedia › Technology and the built world › Transport and spaceflight › Road transport › Automobiles › Automobile manufacturers and marques*
*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license