Overdrive in Subarus, like just about every car with an automatic transmission built in recent memory, is built into the routine working of the transmission. Your transmission selector, if it's like mine, has a "D" for drive then the next digit down is a "3". Choosing the "D" allows the vehicle to access overdrive when appropriate. Driving with "3" as your chioce does not allow the overdrive to work. --Ken
Subaru does not use a separate overdrive unit, if that is what you are asking. For many years, overdrive is simply another gear in the transmission.
Subaru Outback was created in 1995.
The Subaru Outback is sold in the US.
The 2006 Subaru Outback has 16 valves.
The 2013 Subaru Outback has 16 valves.
The 2002 Subaru Outback has 16 valves.
The 2001 Subaru Outback has 16 valves.
The 2012 Subaru Outback has 16 valves.
The 2011 Subaru Outback has 16 valves.
The 2005 Subaru Outback has 16 valves.
The 2007 Subaru Outback has 16 valves.
The 2004 Subaru Outback has 16 valves.