Transmission or ?

Not sure if this is a transmission problem or something else. I have a 96-ford explorer with 196000 mile and it is an automatic. The problem is when I slow down to speeds between 60 to 50 and 2000 RPM, I get this load whine and the RPM drop to 1000. You can get it to stop by giving it a touch of gas. This same problem happened about four months ago and the guy at Ford said that it was the hold back in the transmission and going down hills the valve body might be leaking and causing the hold back to roar. We where on vacation at the time and they said that it would not hurt to drive it. So we continued to drive it on our vacation and it quit never happened again until now. Any ideas? :confused:

I got this fixed. It was a fork in the tranfer case that needed to be replace.