Mo. Rev. Stat. § 408.557: Notice required before deficiency action may be commenced.

When a lender sells or otherwise disposes of collateral in a transaction in which an action for a deficiency may be commenced against the borrower, prior to bringing any such action or upon written request of the borrower, the lender shall give the borrower the notice provided in section 400.9-614 for consumer goods transactions or section 400.9-613 for all other transactions that are not consumer goods transactions.