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    Fuzzy match across codes, option descriptions, and model aliases. Every result is graded and, where the factory documents it, cited.

    Source document

    docs/rpo/buick/regal-century.md

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    Rendered verbatim from the reference. Factory citations shown as ⛭ GM Heritage — …. For filtering, badges, and crosslinks, use the interactive Regal / Century page.

    Buick Century / Regal (1973–1982)

    Covers the Colonnade A-body Century and Regal (1973–77) — including the Century Gran Sport and the last 455 Stage 1 cars — and the downsized G-body Regal (1978–82) with the turbocharged Sport Coupe and the 1982 Grand National. (Pre-1973 A-body GS cars: see skylark-gs.md.)

    By this era Buick order paperwork used corporate RPO codes; the old two-character dealer ordering codes were gone.

    Years 1973–1974 — Century Gran Sport / Stage 1 {#year-1973}

    Code Description Years Models/Notes Confidence
    — (Gran Sport pkg) Century Gran Sport: appearance/handling package on Century Colonnade coupe; 350 or 455 1973–1975 Century; GS name moved from Skylark line confirmed
    — (Stage 1) 455 Stage 1 engine option: big-valve heads, hotter cam, posi; last Stage 1 year 1974 1973–1974 Century GS; 1973: 728 built (92 four-speeds); 1974: 478 Stage 1 of 579 GS 455 confirmed
    V (VIN) 5th VIN character V = factory Stage 1 455 (engine codes XS '73, ZS '74) 1973–1974 Century GS Stage 1 confirmed
    M20 Muncie 4-speed manual w/ Hurst shifter 1973–1974 Century GS (92 in '73) confirmed
    M40 Turbo Hydra-Matic 400 1973–1974 Century GS 455 confirmed
    G80 Limited-slip differential 1973–1977 Century/Regal confirmed
    CC1 Removable roof hatch panels ("Sun Coupe" folding top used distinct pkg; 45 GS Stage 1 Sun Coupes in '73) 1973 Century single-source
    L34 / L32 350 4-bbl / 2-bbl V8 1973–1976 Century, Regal single-source
    F41 HD suspension (Var. 2) 1973–1977 Century/Regal single-source

    Years 1975–1977 {#year-1975}

    Regal split off as the top Colonnade coupe (1975 as Century Regal, own series 1976–77). Performance options faded; applicable corporate RPOs from the TeamBuick 1970–76 Buick list:

    Code Description Years Models/Notes Confidence
    LD7 231 V6 (odd-fire era) 1975–1976 Century, Regal single-source
    L32 / L34 / L76 350 2-bbl / 4-bbl V8s 1975–1977 Century, Regal single-source
    L72 455 2-bbl V8 (final big-block Colonnades) 1975–1976 Century/Estate applications single-source
    M29 / M38 / M40 THM-200 / THM-350 / THM-400 1975–1977 Century, Regal single-source
    BW6 Exterior decor package 1970–1976 A-body single-source
    CB5 / CO4 Vinyl padded roof, full / rear 1970–1976 Century, Regal single-source
    N33 / NK3 Tilt column / sport steering wheel 1975–1977 Century, Regal single-source
    PE1 / PE2 Polycast wheels 14x7 / 15x7 1974–1977 Century, Regal single-source
    C60 / C61 A/C manual / automatic 1973–1977 Century, Regal single-source
    A31 / AU3 Power windows / power door locks 1973–1977 Century, Regal single-source

    The 1976 Century Free Spirit Indy Pace Car carried the turbo V6 in pace car form only (not sold to the public with the turbo) — no RPO.

    Years 1978–1982 — G-body Regal / Turbo Sport Coupe {#year-1978}

    Code Description Years Models/Notes Confidence
    LC8 3.8L V6 turbocharged, 4-bbl Quadrajet (165 hp '78, 170 hp '79–'80) with Electronic Spark Control knock sensor — industry first 1978–1983 Regal Sport Coupe (30,508 turbo Regals in '78); 2-bbl 150 hp version offered 1978 only (its separate RPO not confirmed) single-source
    LD5 3.8L (231) V6 2-bbl, naturally aspirated (105 hp) 1978–1982 Regal, Century (std.) confirmed
    — (Sport Coupe decor) Sport Coupe decor package: blackout treatment, Designers' Accent paint, turbine wheels 1979 Regal Sport Coupe single-source
    Y47 Performance package (released mid-1981): dual-resonator exhaust, higher-stall torque converter, 3.08 rear gears; carried into 1982 (3.08 + exhaust made std.) 1981–1982 Regal Sport Coupe single-source
    Y44 Sport Coupe Decor Package: Designers' Accent paint, blacked-out grille/wiper arms/bezels, wide rocker moldings, sport steering wheel 1982 Regal Sport Coupe single-source
    N78 Cast aluminum wheels 1982 Regal single-source
    WE2 Grand National package: 215 built, silver/charcoal two-tone, Lear Siegler buckets, front air dam & rear spoiler; 4.1 V6 or turbo 1982 Regal Grand National (code reused for 1984–87 GN) confirmed
    F41 Firm ride & handling suspension 1978–1982 Regal, Century confirmed
    G80 Limited-slip differential 1978–1982 Regal, Century confirmed
    MX0 / M29 Automatic transmission provisions / THM-200 1978–1982 Regal, Century single-source
    — (Century Turbo Coupe) Century Sport/Turbo Coupe: LC8-spec 3.8 turbo in aeroback Century 1979–1980 Century single-source

    Turbo notes (1978–82): Buick's carbureted turbo used ESC knock-retard instead of water injection; 1982 revisions — smaller 0.63 A/R turbo, enlarged downpipe, normally-closed wastegate, exhaust-heated plenum, 5-qt pan, lockup converter; only 2,022 '82 Sport Coupes built. The 1978–82 turbo cars predate the T Type name (1983) and the black Grand National (1984).

    Sources