Thought I posted this already but guess not?

http://cgi.ebay.com/Vintage-Television-TV-Cathode-Ray-Tube-Picture-Tube_W0QQitemZ190348605681QQcmdZViewItemQQptZVinta ge_Electronics_R2?hash=item2c51a938f1

Buyer beware... It's marked “11/21/56 bad Cathode”.

I know where these can be had, NOS RCA I believe.