I was cruising down the highway at 90 mph when all of the sudden I heard a whirling/whining sound. I turned down the radio and then realized that Im losing power to the rear wheels. The engine revs but Im just coasting. When I pulled over and turned off the motor, I can drive the car a little ways if I keep the rpms low, otherwise the engine just revs and I have turn off the car in order for the automatic transmission to engage again. The car is towed home and a couple days later, Im able to drive it around town but the tranny slips. Do I need a new tranny or is there a simpler fix???

Thanks in advance,
Chrix