Hi,
When troubleshooting output drops on an interface I suggest the following:
a) Change the load interval from 5 minute to 30 seconds.
b) Clear the counters.
c) Check continously the output queue, to verify how fast the drop counters increase.
If you are not overutilizing the circuit, maybe you just are running applications that send traffic bursts. This could be translated into output drops as the interface queue is not able to handle these peaks of traffic. If that is the case, you could try to increase the output queue (there is no recommended value), but it might help a little bit.
But if you have bursty traffic there is no much thing to do.
Thanks,
Itzcoatl Espinosa