This unit is a rear acquisition module SAM control unit compatible with vehicles.It is designed for installation on models including X164, W164, and W251 chassis, specifically GL320 and GL350 variants.The unit is compatible with trailer and applications due to its integrated control module for these configurations. Part numbers associated with this unit include 1649005401 and 1649005101.Additional compatible part number references are: 1644403501, 1644404601, 1644405401, 1645400101, 1645401101, 1645402201, 1645407245, 1645407345, 1645407445, 1645407545, 1645407945, 1645408145, 1645408462, 1645408845, 1645408945, 1645409045, 1645409162, 1645409245, 1649004800, 164900540180, and 1649007200. Fits the following models: W115 200 D (1968/01–1977/01) GL-Class X164 GL 320 4MATIC (2006/09–2009/05) GL-Class X164 GL 320 / 350 BlueTEC 4MATIC (2009/12–2012/08) GL-Class X164 GL 350 4MATIC (2010/10–2012/08) GL-Class X164 GL 420 4MATIC (2006/09–2009/05) GL-Class X164 GL 450 4MATIC (2006/09–2012/08) GL-Class X164 GL 500 4MATIC (2006/09–2012/12) M-Class W164 ML 280 4MATIC (2005/07–2009/07) M-Class W164 ML 300 4MATIC (2009/07–2011/12) M-Class W164 ML 320 4MATIC (2005/07–2009/07) M-Class W164 ML 350 4MATIC (2005/02–2011/12) M-Class W164 ML 420 4MATIC (2006/02–2009/09) M-Class W164 ML 450 4MATIC (2009/09–2011/12) M-Class W164 ML 500 4MATIC (2005/07–2011/12) M-Class W164 ML 63 4MATIC (2006/01–2011/12) Not compatible with vehicles equipped with option code 848. After installation, the unit must be programmed using the vehicle's diagnostic tool according to the prompts displayed on the instrument.If an error code is present, use the diagnostic tool to clear it.If the error code persists after clearing, verify that the trailer module switch is turned off—this resolves errors caused by active trailer module settings.Once programming is complete and no error codes remain, the unit functions as intended. Important: This is a non-OEM part.Any brand or model cited is used to denote device compatibility.