you will have to confirm this, but AFAIK the FD ratio of the 07+ 5mt is 3.92. Any 2.5L WRX trans with that same final drive should fit. (2.0L are push style clutch and would need the accompanying clutch and slave cylinder setup.)
05-06 LGT 5mts use a 4.11 ratio so if you got one of those youd have to find a matching rear diff to put in as well.
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