sonoma problems
 

My mom owns a 99 sonoma. recently it began to make a droning noise at highway speed. It gets louder the faster you drive, and is really noticable when accelerating. When i let off the gas it quiets down, but is still there. A local shop told her it was the transmission, and was normal for s-10's to do this. The truck is an automatic with the 4.3l motor. 160,000 kms on it.

Re: sonoma problems
 

I have a '99 Blazer and it has always had some driveline noise. I could never quite decide where it comes from.

Have you tried putting it in neutral and coasting at highway speeds? This would eliminate the tranny form the noise 'chain'. You could find out if its the u-joints or rear end.

Re: sonoma problems
 

axle bearings?
I had one in the shop a few weeks ago where the bearings wore 1/4" into the axle.