how do i know when my transmission is out?

Transmissions generally set a check engine light long before it finalizes its transition to junk. Noises,grinding,slipping,hard shifts,banging into 1st at stops,or stalling the engine,no overdrive are common symptoms in these and buick,and pontiacs as components are same model to model. Always start w the basics check fluid first! This car doesnt have any way to check the level. A qualified shop (dealership) can tell how to check it.

There's a big aluminum thing lying on the road. :)~ Seriously though, an automatic will have many indicators: the engine revs but the car won't move; the fluid is dark colored (instead of red) and smells bad as well as making noises (whining or whirring). There may be metal particles in the fluid. There are a few more indicators but these are more common. What is the car doing to make you ask?