There is none on the regular Ooutback

If it's a Gen 4 car, the filter is behind the glovebox; you need to remove
the clips that hold the glovebox liner in and remove it, the filter is in a
tray near the top.
It's documented in my owner's handbook BTW.
Martin

You could check with your local library.  They might carry, for example,
http://www.epnet.com/ which has lots of databases, one of which is for
car maintenance diagrams.  I forget the name of the automotive repair
database but the librarian should know.  Because it's your public
library, it's free to access (but they have to pay a yearly access fee);
however, if you need to take the data with you then you usually have to
submit the page to the printer and then pay to get the printout.

If it is equipped with a filter (either as a standard feature or an
option) there may be a sticker placed on the 'end' or some other area of
the glove compartment or it's door mentioning it.

My 03 has two seperate pieces in plastic frames.

I think all the outback models are cabin filter 'capable' and indeed,
some folks make their own and install them. They are a little pricey
from the dealer, hownever there MAY be Purolator or other after-market
filters avaible now - dunno.

Also, there should be instructions at www.cars101.com .

Carl