2005 gmc yukon front drivers side noise question.

[treveiger]

Hey I've got a quick question. We are looking for a vehicle and stumbled upon this Yukon and it's in great shape and good price but the only issue is sometimes when turning or accelerating I hear a slight hum and feel a very slight vibration in the steering wheel. First thing I think is the hub is bad but I'm not sure. I've heard of differentials can go bad too. It's a 4x4 with the option of auto 4x4 or 2wd. Any ideas would be great.