Whirling noise...Ring & Pinion Gear...Transfer case??

I have a 98 C/K silverado 4WD 350.

I'm hearing a whirling noise when accelerating, but the noise stops when coasting when not under load, or if I slide it up in neutral. I can let off the gas, and the noise stops, touch the gas the noise can be heard again.

A shop thinks it's the ring & pinion gear. He took the cover plate off, and said the gears were worn. A friend said it might be the transfer case.

Any ideas?
Thanks.

I have a friend with the same problem, he said U joints. ....That's Just What I Heard

Well, I took it to a 2nd shop. They said it's the rear end also. Could be ring, pinion gear, bearings, any or all. Going to get it worked on tomorrow. I'll try to post back the results.

Sounds like the pinion bearings to me. Mine did it when the truck was new and they replaced the pinion bearings and it has went 170,000 and no noise.

The magnet inside the differential, that is there to pick up lose shavings, broke apart. Bad news is they have to replace all the bearings and gears, to the tune of over $700.

I'd rather had a few small loose shavings in there, than a broken magnet.

Anyone heard of this happening before?

That's to bad although $700 doesn't sound all that bad. Are they replacing the ring and pinion and the spider gears ?? If they are only doing the bearings it sounds kinda high.My 89 fullsize blazer had a carrier bearing race spin on the carrier until the carrier broke. That sure went out with a bang !! And in the middle of nowhere at that. I replaced the bearings, ring and pinion and put in an Auburn(hunk of junk) limited slip positraction carrier and that was $700+ just for the parts. The labor was free because I did it myself and man is that a tedious job. Put it together, check clearances, take it apart, put it together, etc.. etc... until you get it right. I wish I would have paid the $250 they wanted in labor.