Chevrolet Repair: Whining noise from Transmission, metal shavings, necessary thanks

Question
I have a '98 Chevy Z-71 5.7. When I put the truck in drive or reverse, I hear a whining noise.  When I accelarate it gets louder. When the truck in in park or neutral, there is no noise.  I had the transmission rebuilt almost 3 years ago.  I have been told there is a pump in the transmission that is bad or going bad.  If this is the case, will the entire transmission have to be rebuilt.  Is it one of those things that since you are in there may as replace everything.  I have also been told that if the pump is bad and there are not any metal shavings in the transmission, then a rebuild is not necessary.

Thanks in advance for your help.

Answer
Usually only a manual transmission will whine. If you can you need to try and see if the whining is come from the transmission or the transfer case. Also if the pump itself is going bad you would more than likely be leaking fluid and it probably wouldn't shift right. It sounds to me like you might have an internal bearing going out. And yes if your in there and you have the money it probably wouldn't hurt to have the transmission and transfer case gone through.