No mention of a block heater in the service manual.
It appears that they install heaters on the left side rear of the engine. Of course this type of heater plugs in to household power so if you have one it should be fairly easy to find the cord/plug and trace it back to the heater.
The 2008 Subaru Outback is a gas-powered vehicle.
The 2008 Subaru Outback has a 5-speed manual.
The 2008 Subaru Outback has a flat 4 engine.
The 2008 Subaru Outback is 15 ft. 9 in. (189 in.) long.
The 2008 Subaru Outback runs on regular unleaded.
The 2008 Subaru Outback's turning circle is 35.4 ft..
The height of the 2008 Subaru Outback is 5 ft. 3.2 in. (63.2 in.).
The 2008 Subaru Outback has single overhead cam (SOHC).
The curb weight of the 2008 Subaru Outback is 3350 lbs..
The 2008 Subaru Outback has 16 valves.
The 2008 Subaru Outback has 52.6 in. of rear hip room.
The 2008 Subaru Outback has 53.7 in. of rear shoulder room.