FP The Fleece Performance TapShifter allows you to shift your 2001-2005 GM 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. The TapShifter can be used in the gas or diesel 2001-2005 trucks with an Allison Transmission. 2003-2005 GM/Allison TapShifter Fitment: 2003 Chevrolet Silverado 2500 HD Base 2003 Chevrolet Silverado 2500 HD LS 2003 Chevrolet Silverado 2500 HD LT 2003 Chevrolet Silverado 3500 Base 2003 Chevrolet Silverado 3500 LS 2003 Chevrolet Silverado 3500 LT 2003 GMC Sierra 2500 HD Base 2003 GMC Sierra 2500 HD SLE 2003 GMC Sierra 2500 HD SLT 2003 GMC Sierra 2500 HD WT 2003 GMC Sierra 3500 Base 2003 GMC Sierra 3500 SLE 2003 GMC Sierra 3500 SLT 2004 Chevrolet Silverado 2500 HD Base 2004 Chevrolet Silverado 2500 HD LS 2004 Chevrolet Silverado 2500 HD LT 2004 Chevrolet Silverado 2500 HD WT 2004 Chevrolet Silverado 3500 Base 2004 Chevrolet Silverado 3500 LS 2004 Chevrolet Silverado 3500 LT 2004 Chevrolet Silverado 3500 WT 2004 GMC Sierra 2500 HD Base 2004 GMC Sierra 2500 HD SLE 2004 GMC Sierra 2500 HD SLT 2004 GMC Sierra 2500 HD WT 2004 GMC Sierra 3500 Base 2004 GMC Sierra 3500 SLE 2004 GMC Sierra 3500 SLT 2004 GMC Sierra 3500 WT 2005 Chevrolet Silverado 2500 HD Base 2005 Chevrolet Silverado 2500 HD LS 2005 Chevrolet Silverado 2500 HD LT 2005 Chevrolet Silverado 3500 Base 2005 Chevrolet Silverado 3500 LS 2005 Chevrolet Silverado 3500 LT 2005 GMC Sierra 2500 HD Base 2005 GMC Sierra 2500 HD SLE 2005 GMC Sierra 2500 HD SLT 2005 GMC Sierra 2500 HD WT 2005 GMC Sierra 3500 Base 2005 GMC Sierra 3500 SLE 2005 GMC Sierra 3500 SLT 2005 GMC Sierra 3500 WT