Oshkosh Corporation is listed on the U-S Postal Service website as one of five finalists competing for a $6.3 billion contract.
The winning company will produce a fleet of next-generation mail delivery trucks.
The Wisconsin company was part of a group that produced 50 prototypes over the last four years, creating vehicles with new technology, hybrid engineering and able to run on alternative fuels.
Oshkosh is partnered with Ford Motor Company as it goes for the six-year contract.
Testing was completed in March and the Postal Service is expected to announce its choice later this year.
