<Tr> <Th> Predecessor </Th> <Td> 4L60 - E / 4L65 - E 4L80 - E / 4L85 - E </Td> </Tr> <Tr> <Th> Successor </Th> <Td> 8L90 </Td> </Tr> <P> The 6L80 (and similar 6L90) is a six - speed automatic transmission built by General Motors at its Willow Run Transmission plant in Ypsilanti, MI . It was introduced in late 2005, and is very similar in design to the smaller 6L45 / 6L50, produced at GM Powertrain in Strasbourg, France . It features clutch to clutch shifting, eliminating the one - way clutches used on older transmission designs . In February 2006 GM announced that it would invest $500 million to expand the Toledo Transmission plant in Toledo, Ohio to produce the 6L80 in 2008 . </P> <P> Gear ratios: </P>

When did the silverado get a 6 speed