SOUTH BEND, Ind. (AP) — Two northern Indiana automakers have been awarded contracts to build prototypes for the next generation of U.S. Postal Service vehicles.

The South Bend Tribune reports that AM General, based in South Bend, was awarded an $8.75 million contract while Utilimaster, based in Bristol, was awarded a $3.67 million contract. Overall, the Postal Service awarded six companies $37.4 million in contracts.

The Postal Service plans to replace its aging fleet with advanced vehicles that provide better fuel efficiency and zero-emission capability.

The companies will be given a year to design and build the prototypes, which will have a variety of sizes and drive configurations. A total of 50 will be developed. The Postal Service will test the vehicles over a six-month period before awarding replacement contracts.