I seem to remember someone here needing this # tube before--on this site
One is on Ebay now. Claims to be good:

http://www.ebay.com/itm/American-Standard-17CP4-Original-CRT-Picture-Tube-1953-NICE-/111393696609?pt=US_TV_Boards_Parts_Components&hash=item19ef94eb61.

Worth saving, if good, though I think only used by RCA. Looks like an old rebuilt.
Bill Cahill

Worth saving, if good, though I think only used by RCA. Looks like an old rebuilt.
Bill Cahill

Admiral and Motorola used them as well.
It seemed the 17TP4, self focused CRT, was more widely used. You can use the 17C, but a magnetic focus unit has to be used.

Is this the same American Standard I associate with bathroom fixtures? Gives "down the tubes" a whole new meaning.