i think your problem is something else. either it being that something is going on with the case to cause the gears to not mesh right. or maybe you just so happened to get a bad batch of gears...kinda a long shot but it happens. you can almost guarantee that a stock output will be the first thing to break after big tires and 4.7s. specially if your not bound up. make sure all the c clips are on where the gear shafts go into the bearings. they send the gear without them and lots of people forget to take their old ones off and put them on the new set. since their helical cut gears.. if the clips aren't in it can cause the gears to walk off the bearing a bit. wouldn't take much either. also if they were forgotten everything would work completely fine until there was enough pressure for them to move.
unless i missed that you are running a chromo rear and front output then this is either shitty luck or i think something else is wrong.
also (not taking to you pumpkin toy) but you cant even compare a 4.7 to a stock 2.28, completely different with the amount of stress it sees. also there are no other brands out there besides t.g.. and obviously mc makes the top of the line gearsets.