The Fleece TapShifter allows you to shift your 2001-2005 Allison Transmission with the touch of a button just like the 2006 and newer trucks. Perfect for towing, drag racing, daily driving and everything in-between, the TapShifter installs in no time and provides factory-like operation, functionality and styling. Installation:The TapShifter installs using OEM high quality connectors for a completely plug and play installation in less than 30 minutes.Operation: TapShifter Operation is very straight forward. To downshift you'll simply depress the "-" button on the shifter. To upshift you'll press the "+" button. The TapShifter will allow you to select a range with the shift lever and then tap up and down without worry of tapping to a higher range than selected. This feature is great for sled pullers who do not want to shift to 4th gear on the track!Features: Easy Plug & Play InstallationLimits Up-Shifts Overdrive Disable*Command Downshifts Decrease Gear Hunting