If you think it will fit, I *might* know where you can get the all-glass equivalent 19DP4, NOS. It's a 1/4" larger diameter, and also a bit "fatter" because the O.D. extends further rearward before it tapers to the neck. Very unusual glass tube, because the cone is flat like a metal tube.
I got a quote recently from Hawkeye on a metal tube (16EP4): $450!!!
Specs:
http://tubedata.tigahost.com/tubedat...7/1/19DP4A.pdf
Lemme know.