Yes both factory units are single DIN, so you'll be able to replace the factory stereo easily. Subaru can provide a DIN "cover plate", but with the lack of storage, I though it made more sense to install a "pocket"
I went to my local car audio specialist and asked him if he had any "extra" pockets from Subarus that he had kept after installaing a new stereo. He happened to have 2 pockets, both from Legacys, I believe. He sold me both for $10. (The Subaru dealer wanted $5 plus shipping for the (cover plate).
I had to make some minor mods to the pocket. Using a dremel tool, I cut off the 2 tabs that were on either side of the pocket, so that it would fit into the SVX chasis. I then installed the new Stereo, and bolted into the chasis. I slid the pocket into the chasis, beneath the stereo, and lined it up so that it was even with the face of the stereo. I marked where the screw holes in the pocket were, removed the pocket and stereo, and drilled holes int he chasis. Re-installed the stereo, insereted the pocket, and screwed it in place.
All in all, it took about 20 minutes (after the chasis and stock radio were removed from the car). I then performed the same procedure on my dad's SVX. I think it came out great, and provided more storage space.
You can check out a pic of it on my memeber profile at the I-Club, or... http://18.104.22.168/MembersList/Vie...?MemberID=1530