2001 Silverado 2500 HD Base engdesig: LB7, engvin: 1, Manual Transmission, 6-Speed, transmfrcode: S6-650/ML6. 2005 Silverado 2500 HD (submodel: LS, LT) engdesig: LLY, engvin: 2. 2001 Silverado 2500 HD LT engdesig: LB7, engvin: 1, Automatic Transmission, 5-Speed, transmfrcode: 1000/M74.
