Tranny

Any transmission experts in here? 96, 3100 engine: Driving to work this morning, and hit the gas in stop-and-go traffic, and didn't move, the car just revved. I put the car into drive instead of overdrive, and it moved flawlessly. I later shifted back into OD and it worked fine for the remainder of the trip, but as soon as I got to work I checked the fluid (which got changed approximately 15K ago, and was FOR SURE bright red about 5K ago) and was full, but it was the color of new motor oil and smelled burnt. I'm thinking the trans is junk at this point......Any thoughts?

Dark brown indicates overheated fluid from internal slippage, nuff said.