Only front wheel drive?

[Slowrunner]

Hello there, newbie here just got an ax-10 rtr for christmas and I think I already broke the rear ring and pinion. Motor spins the rear drive shaft, but not the wheels. Wheels spin freely by hand, no unusual noises. is this the problem?
I am out of town with it right now and the big bag of extra parts is at home unopened. My question is this, does anyone know if there is a spare set of gears in that bag? Also, I noticed there are heavy duty gears on the market, should I just upgrade if these have already broke? the weather has been pretty crummy here so I havn't even used it much. Lastly is it terribly difficult to change out the gears? Sorry for all the questions. I am in Farmington NM for another day and their hobby shop has a bigger selection of axial parts than anywhere in Albuquerque as far as I can tell, so if I need to buy stuff now is the time.
Thanks,
Brian