1999 GMC Yukon Torque converter bad or transmission bad?

I have a 1999 GMC Yukon 5.7L V8, just recently, after coming to a stop at a red light, I began to accelerate and a sudden loud whine came from the transmission, it still drove and I was able to pull off to the side of the road, but after placing it in park, it kept rolling, so I put the E-brake on so it wouldnt roll any further. After sitting for a min, I put the truck in drive and the loud whine came back, and the speedometer jumped to about 15mph, but the vehicle wasnt rolling, and anytime I shifted through the gears, the loud whine continued. Prior to this, the truck ran smooth, the transmission shifted perfectly, there was no high rpms at all, and there didnt seem to be any signs that either the torque converter or transmission was going bad. It has 198,000 miles on it, and its maintained very well with the engine in great shape. Anyone have any ideas as to what this problem may be? Or should I go ahead and plan on a Torque Converter or a new transmission?