MCLEAN INDUSTRIES <MII> UNIT TRANSERS SERVICE McLean Industries Inc said its shipping subsidiary, United States Lines Inc, reached an agreement in principle to transfer its South American service to American Transport Lines Inc, a subsidiary of <Crowley Maritime Corp>. Under the terms of the agreement, United States Lines will lease five vessels to American Transport for 15 months with an option to extend the period up to 10 years, the company said. In return, U.S. Lines will receive a fixed payment and a percentage of revenues for at least three years and possibly as long as American Transport utilizes its vessels and conducts trade in South America, the company said. The companies will consummate the transactions as soon as the required approvals are obtained, McLean said.