This brand new alternator is perfect for your Mercedes GL450 or GL550 from 2008 to 2012. It has an amperage of 180 and operates at 12 volts. The grooves are 6 and the fan is internal, with an internal regulator as well. This aftermarket product has multiple OEM interchange part numbers, including A0131543502, A0141540402, and FG18S016. In order to ensure your safety, please be aware that this product may expose you to chemicals such as lead, carbon black, silica, and crystalline, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, please visit www.P65Warnings.ca.gov.