Howling noise while in 4 wheel drive

[Coty]

I’ve got a 2003 Silverado,  bought it used and had to use 4x4 the other day on snowy rd. While in 4hi or auto 4 wheel it was a loud howl while accelerating but got pretty quiet when I let off gas and also had vibration under driver side floor board. Anyone heard of this or know where to start looking? Thanks 

[dsr611]

Start by looking and asking the question in the correct sub-forum...this sub-forum is to make comment on the GM-trucks site, not for questions on vehicles.

 

http://www.gm-trucks.com/forums/forum/3-1999-2006-2007-2013-chevrolet-silverado-gmc-sierra-1500/