, /PRNewswire/ --Â Allison Transmission is proud to announce its 4500 Rugged Duty Series (RDS) fully automatic transmission has been successfully integrated with the Cummins X15N natural gas engine in Kenworth T880 tractors. The pairing sets a new standard for sustainable heavy-duty transportation, delivering exceptional power and innovative technology. Allison Transmission is proud to announce its 4500 Rugged Duty Series (RDS) fully automatic transmission has been successfully integrated with the Cummins X ...