Think I transposed the letters which should be VFD for "vacuum fluorescent display".
The tubes that I can see/find easily are labeled "Philco 7P" and "Sylvania 6DQ4."@kjmelvin The Sylvania tube is a rectifier in the power supply and does not amplify. The 7P is not the tube type of the Phillips tube- that seems to be a house number. But it suggests an older tube! Look elsewhere on that tube to see if you can find the number. Its often etched into the glass on the side.
@kjmelvin I run a small tube amp manufacturing company called Atma-Sphere. If you want, send me a photo to my email address. You can find that on the contact page of our website www.atma-sphere.com
Maybe we can get to the bottom of this. If you have the schematic diagrams and parts, I'm sure it would not be hard to sort this out. I have to admit I'm curious what the VFD tube is doing in a project like this.