Oops! I totally thought you were referencing the frame of the cabinet itself. I was looking at the speaker, and saw the ink-stamped codes.
Mine reads: 0126 08 504, and 4 78
So, I would dare say late 70's(in this case, my cabinet just turned 30! Any chance Hallmark makes cards for this?), but I don't know. I can check my beta lead to see if the same ink-stamping might be on it, as it's made from the same period, in the same style(red sun logo).
Hope that helped!