https://modernpublicfleet.com/gm-teases-new-8-3l-duramax-diesel-v8-for-2027-silverado-hd-and-sierra-hd/ Modern Public Fleet en 2026-09-21T09:30:42-06:00 GM Teases New 8.3L Duramax Diesel V8 for 2027 Silverado HD and Sierra HD