Frnt and rear gear box

[WAYNE8004]

I have noticed that my trucks gears are slipping in the front and rear box. I seen on ebay the gear set they have, anyone have any ideas what gear it could be?

 

[CyberVet65]

Slipping? As in under power they don't run?

 

[topblissgt]

gears don't 'slip'. My guess is that the pinion gear set screw is loose