A whine or buzzing noise during transmission operation is a bit more serious. A bearing or other issue inside the transmission could be causing this type of noise. If that's the case, I would recommend you take it to a specialist to be diagnosed. I say this because automatic transmission diagnosis often involves special tools and years of experience to be done properly. If you're intent on just swapping out your failed transmission with either a rebuild or salvage replacement, then go for it. Replacing automatic transmissions is not nearly as difficult as rebuilding or repairing them. Rebuilding automatic transmissions is best left to those experienced people with the proper tools. Trust me on this.
In summary, automatic transmission noises limit your options. If you find that you have an automatic transmission noise, I would suggest taking it somewhere to be properly diagnosed. As I said, you need specialized equipment to diagnose them properly. These are tools that are not often loaned out at your local auto parts store. I'll get into automatic transmission diagnosis more in the Transmissions article.