1987 cutlass supreme transmission shifting problem

my transmission won't shift, it just hangs, so I've resorted to manually shifting it. I am going to do a drain and fill with a new filter too, but I was told that it could be the transmission module. I cannot find the transmission module on the actual transmission, anyone know where I could get a diagram or happen to know where it's located?

There is none on an 87, only newer units, check vacuum to the modulator if so equipped and check the TV cable and/or adjustment. BTW in the future post engine and trans type.

I don't know what transmission I have. How do I figure that out? The only number we found was 87K6B20144

What engine? (again) Does it have overdrive, a circle around the shift indicator in dr. Based on these questions I would suggest you will have difficulty fixing this kind of problem yourself.

my engine is the 307 V8 5.0L carb. I don't know anything about transmissions, I can do somethings to engines and know more about engines. my daughters father is ASE certified, but hasn't done much transmission work, let alone on anything this old. You seem to know alot, which is the help I was looking for. No overdrive, just D, 1, 2. Thank you for replying. He is going to do the drain and fill and replace the filter, the fluid is bad.

That trans is a 200c, 3 spd lock up convertor.

thank you for the type of trans, it is very helpful.