Having purchased props (and sold a few) in the past, I wouldn't count on anything being more than a shell. Set designers care about outer appearance, period, and when a TV is portrayed as playing, the image is easily faked.
TVs appeared fairly often in that show. I wonder what happened to the other prop sets?
Pet Peeve: as much as I loved "Mad Men,' it invariably showed TVs playing with incessant and exaggerated problems -- jumping vertical or horizontal, etc., or reception suddenly crapping out for no reason. Yes, TV reception wasn't ideal back in the day, but it sure wasn't THAT bad!
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html