Are Metal Trans Gear necessary E-maxx?

[RCHabit]

I fixed my problem..
My diagnosis is, The inputshaft gear broke a tooth off and then that piece took out 1st gear. The rear diff was also wiped out. I think the diff locked up and shock went to the tranny or Vise versa.

Anyway, its all back together with new heavduty diff gearsets and the stock replacement parts for the trans.