[sperry]

Um, WRX's don't have transfer cases per se. I'm assuming you're talking about the center differential at the back of the gearbox? But the talk of "breaking some teeth" sounds like the transmission gears themselves, since there aren't any teeth in the center diff.

You're basically looking at replacing the entire gearbox. I'm not up on the gear ratios these days, but I would guess you should be able to get anything from an '02 to probably a current WRX, Legacy, or Forester. The newer the better (in terms of strength) but again, you'll have to make sure you pick the proper gearbox that matches the 3.90 rear-diff in your WRX (or also get the matching diff).

NASIOC likely has tons of good info in their tech forums about which gearboxes will match a 3.90 rear-end. I'd start there, and keep an eye out locally or in Sacramento for a used gearbox. Anyone swapping to a 6MT (that isn't doing it because they grenaded their 5MT) would potentially have what you need.