I have an 89 Cad Deville. Starts and runs good. When I put it into R or D, you can feel and hear the car engage, but when you apply gas, it doesn't go, just will slightly move if on level ground. Like it's trying but no power getting to the wheels. Any thoughts anyone?

 

Is it full of fluid, and what does the fluid look/smell like? Sounds like the trans is toast, if you can feel it engage, but it won't move the vehicle....