If you created enough torque shear to snap a half shaft you were going a lot faster than 30 mph and you have probably totaled the transmission. I would suggest that you draing the oil out of your transmission and see if any metal debris come out. If it's perfectly clean you may have got lucky, if it's full on chunks you'll need to check junkyards for a usable ST Transmission. BTW, Mountune does sell these transaxles but they aren't cheap, IIRC about 4400 bucks.