renato.design

Plenum™

Decode factory numbers and documents on muscle and pony cars. With uncertainties and citations marked.

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Web-only, phone-first. The decode engine runs in your browser. Photos never leave your device — the OCR is local. No accounts, no analytics, no server in the critical path.

Two-car compare in Plenum: Phil Renato's 1991 Pontiac Trans Am GTA in the foreground next to his 1970 Dodge Super Bee
What it is

A deterministic decoder for the factory production documents on Mopar muscle and GM third-generation F-body cars — with more to come. Give it a VIN. Or pick a document type — fender tag, broadcast sheet, SPID label — and it will try to read the codes off your car into the textbox.

The decode returns a structured read — engine, transmission, paint, plant, package — with a citation under every code and a confidence tag that says how sure it is. factory-documented, registry-corroborated, registry-attested, forum-consensus, single-source, disputed. Damaged sheets get partial decodes. Missing cells are marked, not invented.

What it covers now
Mopar muscle, 1968–1974

B-body · E-body · A-body

Production broadcast sheets and fender tags. ~150 sales codes. Plant overlays for Lynch Road, Hamtramck, Jefferson, Belvidere, Newark, St. Louis, LA, and Windsor. Year-aware engine, paint, and option vocabularies. Engine-letter ↔ engine-sales cross-walk between the VIN and the fender tag.

GM third-gen F-body, 1982–1992

Camaro · Firebird · Trans Am · GTA

SPID labels and door plates. Z28, IROC-Z, Formula, Trans Am, GTA, the 1989 20th Anniversary Turbo. RPO-coded, with California vs. 49-state and export variants tagged. Position-by-position VIN decode through 8th-character engine, 10th-character year, and 11th-character plant.

How Plenum is different
Honest uncertainty Every code carries a confidence tag and a citation. When two sources disagree, both readings show. Plenum does not adjudicate fender-tag authenticity from a photo.
Plant-aware A 1970 Lynch Road broadcast sheet is not a 1970 St. Louis broadcast sheet. The schema knows the A34 callout often goes missing on Lynch Road tags and treats blank A34 cells differently there.
Year-aware The A32 axle code means one thing in 1970 and another in 1971; Plenum tracks the difference. The N96 Air Grabber doesn’t exist on a 1970 convertible because the fresh-air hood plumbing required a hardtop roof — Plenum says so.
Damage-friendly Burned, torn, marker-defaced sheets get partial decodes. The cells that survived get cited. The cells that didn’t are marked destroyed, never fabricated.
Local, deterministic The decode engine is pure TypeScript in your browser. No server hop, no LLM, no telemetry. Same input, same output, every time. That’s what makes the citations real.
One quiet surface No comments section. No replies. No leaderboard. Plenum is a reference instrument, not a forum — the combative get no audience.
Two cars

Plenum is also how I keep track of my own cars: a 1970 Dodge Super Bee, FE5 bright red, V-code 440 Six-Pack, built at Lynch Road. And a 1991 Pontiac Trans Am GTA, medium green metallic, LB9 5.0 TPI, T-tops, C&C fiberglass hatch, owner-converted black-cloth interior. The demo decode is my Bee.

Screens
The Plenum decode form: paste a VIN or pick a document type — VIN, Mopar fender tag, Mopar broadcast sheet, GM SPID label.
Decode. Paste a VIN. Or pick the document you have and read the codes off it. Photo intake opens with the document modes; OCR runs locally.
A decoded 1970 V-code Super Bee — VIN row, engine, paint, trim, plant, all surfaced with their codes and meanings.
Result. Codes resolved into meanings, with the confidence tag on each cell. Paint and trim render as chips that match the factory color. Citations are one click away.
Plenum's models browser — a list of muscle car families with production counts and option dimensions.
Models. Browse production counts by configuration. Pick a model and a set of options; Plenum reports the count for that combination when it’s publicly tabulated, and says when it isn’t.
Two-car compare: a 1991 Pontiac Trans Am GTA and a 1970 Dodge Super Bee in Phil Renato's driveway.
Two-car compare. Stand two decodes side by side. A V-code Super Bee next to an LB9 GTA — same screen, twenty-one years apart, two completely different document genres, both legible.
Plenum's concordance: three movements per car — Witness, Reading, Mechanism.
Concordance. Witness is what the document literally says. Reading is the long form on the kind of car. Mechanism is how Plenum knows any of this — the per-schema essays, the citation posture, the disagreements between sources.
Not what it is

Plenum decodes numbers against known numbers. It does not authenticate the parts on the car today. Those are different questions, and the gap between them is one of the oldest in the field. Theseus’s ship, restored a plank at a time. The factory documents tell you what came down the line in 1970, according to the Big Three. They do not tell you what is bolted to the unibody now. Plenum reads the first question; the registries and the marque experts adjudicate the second.

Plenum is not a registry, not a price guide, not an authentication service, not a forum. The codes themselves are facts and unrestricted; the compilation, the citation discipline, the honest-uncertainty layer, and the writing on top are our work product.

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