The 87-89 GT's have a functioning 4-light warning pod on the lower right of the cluster. In it is has a low fuel light, low oil light, low washer fluid light and a low coolant light.
In the LX it's empty and does not work. You can swap the little pod in. It connects to the cluster. I have one in my car. So far only the "Low Oil" light works. It comes on with the one in the gauge pod. I have not got the other lights to come on, but i don't have a coolant sensor, or the correct washer bottle with the sensor so i bet if i got those they would work.
I don't have the guts to try to see if the low fuel light would ever come on.
I've been trying to find an 87-89 GT washer bottle with the sensor forever...no dice