Okla. Stat. tit. 36, § 3637

This act shall not apply to any policy covering motor trucks operated by a motor carrier as defined in 47 O.S. 1961, Section 161, as amended, where the named insured has employees who operate motor trucks or to any other commercial automobile liability policy covering motor trucks where the named insured has employees and such employees are covered by workers' compensation on the effective date of the policy.