Kinda pricey for an untested CRT. Maybe someone in the area can check it out ?

http://cgi.ebay.com/GIGANTIC-RCA-Electron-0-52-Television-Tube-20-x-15-/160474818566

Looks too short for a 16AP4 Pix1 ... Perhaps 16EP4 or 16GP4?
jr

That's a very pricey 16GP4.
Bill Cahill