I'm partly just documenting stuff for people to refer to in Searches, and partly asking questions. Heater controls on '78s a '83s are different. As you can see from the pictures, the '78 controls have an additional lever for fan speed. According to my understanding, they also have a light in the upper right corner which turns on and off according to fan operation. It is my understanding the '83 controls lack this last feature. I like that feature, so I am removing the '83 controls in favor of the '78 controls. The car is a 1978.
1983 Controls
1978 Controls