RPOARCHIVE
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    Fuzzy match across codes, option descriptions, and model aliases. Every result is graded and, where the factory documents it, cited.
    M38 / M40 Confirmed

    Buick · Regular Production Option

    THM-350 / THM-400 (RPO)

    Years 1970–72 Models 1

    Documented applications

    This page aggregates every documented appearance of M38 / M40 in the Buick reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.