The 6-Speed Allison found in your 2017, 2018 or 2019 Chevy Silverado or GMC Sierra earned its reputation for excellence largely because of the advanced electronic control provided by the TCM (Transmission Control Module). Changing that factory calibration is especially important for you when you modify your truck and/or install ECM Tuning. Custom TCM Tuning gives you quicker shifts, smoother operation and an overall a better driving experience.