My 1997 gmc jimmy has started making a huming sound only when I'm in 2wd. It sounds almost exactly like a wheelbearing. To make a long story short I have replace both front wheel bearings, axleshaft bearings and seals, brand new tiresand changed all fluids. I also did rear bearings as well. All u joints are tight as well as all pinion bearings front and rear. It sounds the worst around 40mph. It sounds like it's the front passenger side that's making it. As soon as it's in 4wd it goes away. I have checked the vacuume switch on the t-case and make sure it wasn't partially engaging. That is new and working. I put it up on jackstands and checked to make sure nothing was hanging up in 2wd and it all seemed fine. I'm at a loss. The only thing I noticed is both cv axles coming out of the front different seem to have a bit of up and down play. Those inner bearings are new but the axles are not. Could they be messed up?


Also forgot to mention that the sound doesn't go away or get quieter when slowing down, braking, accelerating or turning. It starts making sound around 20 to 25mph.


Thanks for your help