So the tranny started to make this howling sound yesterday morning and it seems to be getting worse the more I drive it. I have never heard this before and it only seems to make the sound between 15-30 MPH and it's only doing it in second gear while down shifting, sometimes I will hear it during acceleration but not as noticeable. The sound is a high pitch vibration, what could it be?

 

I suppose if it were mine, I'd check the oil level, and also the condition of the rubber boot above the transmission.

A torn boot can let in an awful lot of noise.

Do you have the NV5600 or the G56?

If you decide to change the oil, the NV has a magnet in the bottom that you have to pull off the block off plate for the PTO to reach in and get. The G has a magnetic plug.