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.
Lede
The CSX3 cars are the 427 Cobras — the big-block Mark III generation built between 1965 and 1967, and the most aggressive cars the original Shelby Cobra program produced. Approximately 160 genuine 427 Cobras were built; that’s the total commonly cited and the figure to anchor on for any claim about CSX3 rarity. Some cars in the CSX3 range carry the 428 cubic inch engine rather than the 427, the result of Ford’s 427 supply constraints during certain production windows. The MkIII chassis is a redesigned, beefier platform compared to the MkI/MkII CSX cars — wider track, larger tires, and stronger structure to handle the big-block’s torque.
Production span and totals
- Era: 1965-1967, within the broader 1962-1967 Cobra program
- Total CSX3 production: approximately 160 cars (per the Cobra Authority buyer’s guide). This is the canonical "427 Cobra" production number.
- Chassis range: CSX3001 through CSX3360 (approximate; per HANDOFF.md’s existing chassis prefix convention)
Defining mechanical characteristics
- Engine: Ford 427 cubic inch FE big-block V8 (the headline). Some cars use the 428 cubic inch Police Interceptor engine due to 427 supply issues during certain production windows.
- Chassis: redesigned MkIII platform — wider track, larger frame tubes, revised suspension geometry to handle big-block torque
- Suspension: revised front and rear geometry from the MkI/MkII cars
- Brakes: upgraded from the small-block cars
- Body: wider fenders to clear the larger tires; visually distinct from CSX/CSX2 cars
Variants within the family
- 427 standard street — base configuration for road use
- 427 S/C (Semi-Competition) — competition-spec body and chassis but registered for road use. The "Semi-Competition" cars are a notable sub-population that bridges street and race configuration.
- 427 Super Snake — extremely rare. Only two were built: CSX3015 and CSX3303. Both carry twin-Paxton-supercharged 427 engines and represent the most aggressive configuration in the original program.
- 428 cars — cars that received the 428 Police Interceptor engine instead of the 427 due to 427 availability. Mechanically similar to the 427 street cars; the engine swap is the distinguishing fact.
- Competition cars — CSX3 chassis built specifically for FIA / SCCA competition, separate from the S/C street-legal competition spec.
How to identify
- Chassis number prefix: CSX3 (CSX3001 through CSX3360 range, approximately)
- 427 big-block FE engine under the hood is the headline mechanical signature; verify against the chassis number range
- Wider fenders versus the small-block CSX cars
- Revised chassis geometry — wider track is visible from underneath or in the wheel arches
- For S/C cars: look for the competition-spec body features (deeper fender flares, more aggressive bonnet treatment, racing-style fuel filler, FIA-style mirrors)
- For Super Snake cars: twin Paxton superchargers are the immediate giveaway — only CSX3015 and CSX3303 carry this configuration
Notable chassis numbers
- CSX3015 — one of two 427 Super Snake Cobras ever built. Originally delivered as a Competition roadster, converted in 1967 to Semi-Competition / Super Snake configuration. Sold at Barrett-Jackson Scottsdale in 2007 for $5,500,000. (Per HANDOFF.md’s Archetype A lede example.)
- CSX3303 — the second of two 427 Super Snake Cobras ever built.
Additional notable chassis numbers (FIA cars, race-history cars, well-documented street cars) to be added as build articles are written.
Sources
- Cobra Authority buyer’s guide: https://cobra-authority.com/shelby-cobra-a-buyers-guide-to-originals-kits-replicas-tributes-continuation-cars/ — source for the 160-car production total and the 1962-1967 program span.
- SAAC (Shelby American Automobile Club) registry — authoritative source for chassis-specific provenance, including 427 vs 428 engine identification, S/C vs street vs competition configuration, and race history.
Last reviewed: May 16, 2026