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 has a 5-speed manual.
The 2008 Subaru Outback has a flat 4 engine.
The 2008 Subaru Outback is a gas-powered vehicle.
The 2008 Subaru Outback has single overhead cam (SOHC).
The 2008 Subaru Outback runs on regular unleaded.
The 2008 Subaru Outback is 15 ft. 9 in. (189 in.) long.
The curb weight of the 2008 Subaru Outback is 3350 lbs..
The height of the 2008 Subaru Outback is 5 ft. 3.2 in. (63.2 in.).
The 2008 Subaru Outback's turning circle is 35.4 ft..
The 2008 Subaru Outback has 16 valves.
The 2008 Subaru Outback has 54.4 in. of front shoulder room.
The 2008 Subaru Outback has 39.1 in. of rear head room.