Check out this picture of a 68 / 69 heater box from firebird central.
http://www.firebirdcentral.com/1968_...y_p/htr-60.htm
You could also go to heartbeatcity.com to see what they have for a 69 Camaro. I would think it's the same. Note that your boxes are missing the plastic piece that directs the flow of air.
There are at least two different styles of that part. One is long and mounts on the long flat surface that is prominent in your picture. See this link for a picture of it mounted to the box.
http://www.firebirdcentral.com/1967_..._p/duc-150.htm
It is used to divert air when you have a console. A much shorter piece is used on the heater box when there is no console.