[Hondasucks]

Well, you have a couple of options:

1) Figure out what your transmission came out of, and get a matching rear diff to swap in your car. Depending on what it came out of, you might be able to find a car in the junkyard with a limited slip rear end that you can get, otherwise you will either have to just swap in an open rear end, or change the gearing in your rear end (Which you will need to have a shop do, unless you have the proper tools & knowledge to set up a rear end). Some Outbacks and Foresters have LSD, but they are not marked on the case, you will have to rotate one rear wheel and see if the other one turns the same direction (LSD) or the opposite direction (open). Most Outbacks are 4.11:1, most Foresters are 4.44:1

2) Take the front differential and housing off your old transmission and swap it onto your new one. This is not very hard, but you will need some pretty big sockets to get the pinion shaft out. This could also be done by a Subaru dealer if you aren't comfortable taking your transmission apart. It's not super difficult, but it is easy to booger up the transfer clutches when reassembling the rear case. If you go this route, I would order some new transfer clutches and a torque converter shaft tube from Subaru.