Seed file — full Archetype C buildout deferred to Phase 1. Style notes for the Writer are thin; user/co-worker domain knowledge should augment before this file is loaded as authoritative Writer context.
The COB and COX chassis prefixes are AC Cars’ own pre- and parallel-Shelby chassis numbering system. They appear on AC-built cars that fall outside the standard Shelby-American CSX program: the AC Ace and Ace-Bristol roadsters that preceded the Cobra, AC-Cobra cars built for non-US markets (sold through AC rather than through Shelby American), and certain right-hand-drive variants. AC Cars manufactured at the Ferry Works facility in Thames Ditton, Surrey, England — a site they occupied for approximately seventy years.
Background — AC Cars before Shelby
The COB / COX numbering predates the Shelby Cobra by decades and belongs to AC Cars’ independent chassis-numbering tradition. Key facts from the AC Cars history:
- John Weller, the designer who founded the company that became AC Cars, was born November 28, 1877
- 1900 — Weller Brothers Engineering formed in West Norwood, London
- 1907 — renamed Autocarriers, Ltd; the "AC" abbreviation was adopted as the company logo and brand
- 1911 — moved operations to the Ferry Works facility in Thames Ditton, Surrey, England (approximately 70 years of production from this site)
- 1921-22 — Selwyn Edge became Governing Director, then gained full control in 1922
The AC Ace and Ace-Bristol roadsters built at Thames Ditton in the 1950s formed the basis for the Shelby Cobra: when Carroll Shelby partnered with AC, the Ace chassis was the platform Ford V8s were installed into to create the Cobra.
What COB and COX denote
- COB prefix: typically used on certain AC-built cars. The specific usage convention (export markets, right-hand-drive, particular model variants) needs Phase 1 buildout from cited sources.
- COX prefix: a related AC chassis prefix. Same need for Phase 1 source verification of exact usage.
Specific chassis number ranges, the precise distinction between COB and COX, and the criteria for AC-prefix vs CSX-prefix on Cobra-era cars are not detailed in the current cited sources and should be filled in during Phase 1 buildout.
- The three Cobra-era chassis prefixes encode the original target market: COB cars were built for Britain and were originally right-hand drive, COX cars were built for Europe and were originally left-hand drive, and CSX cars were built for the United States and were originally left-hand drive. AC issued the COB and COX numbers from Thames Ditton; the CSX numbers were issued by Shelby American in Venice, California for chassis routed through the United States program. [Source: https://cobra-authority.com/1967-ac-cobra-427-cob6127/]
Production context
- Era: COB/COX cars span from AC’s earliest Ace production in the 1950s through the Cobra-era cars built at AC’s Thames Ditton facility for non-US markets
- Manufacturer: AC Cars at Ferry Works, Thames Ditton, Surrey, England
- Distinct from CSX: CSX chassis cars were sent to Shelby American in Venice, California for engine installation and US distribution; COB/COX cars were typically sold through AC’s own channels rather than Shelby American’s.
How to identify
- Chassis number prefix: COB or COX rather than CSX
- Documentation chain: AC Cars paperwork rather than Shelby American paperwork
- Right-hand drive is more common on AC-prefix cars than on CSX cars (which were US-market builds)
- AC Cars production records (where available) are the authoritative reference for these cars
Detail on visible mechanical or body differences between AC-built and Shelby American cars to be added during Phase 1 buildout.
Notable chassis numbers
To be added as build articles for specific AC-built Cobras and pre-Cobra Aces are written.
- COB6127 was the last Cobra roadster to leave AC’s Thames Ditton workshop. The chassis was originally specified as a gift for AC Chairman William Hurlock but was instead delivered as an unfinished rolling chassis to Ian Richardson of Hills Garage on July 15, 1968. The retired AC workshop crew traveled to Richardson’s garage to complete the interior trim and running gear, finishing COB6127 in private hands. [Source: https://cobra-authority.com/1967-ac-cobra-427-cob6127/]
Sources
- Cobra Authority AC history article: https://cobra-authority.com/the-history-of-ac-cars-and-the-birth-of-the-shelby-cobra/ — source for AC Cars founding history, the Weller / Edge ownership timeline, and the Thames Ditton facility.
- AC Cars production records (historical) — authoritative source for COB and COX chassis-specific configuration, intended market, and original ownership.
- SAAC (Shelby American Automobile Club) registry — for any car that crosses from the AC numbering system into the Shelby world.
Last reviewed: May 16, 2026