Fuel Sending Unit (for use with Aftermarket Lift Pumps) for S&B Replacement Fuel Tanks for 2004-2010 GM Duramax 6.6L LLY, LBZ, LMM is an S&B fuel sending unit intended for the fuel tank and vehicle configuration listed in the product title. It is used to support fuel level reporting on compatible OEM or S&B replacement tank setups, including certain aftermarket lift-pump configurations where noted. Because bed length, tank type, and pump setup affect compatibility, verify the SKU against the current S&B application notes before ordering. Original description written for S&B part 86-2001 without copying manufacturer or reseller text.