Thread size for valves on RJ chassis and 9 pin sockets?

[Mark]

I noticed the holes to mount the valves on RJ's chassis is threaded. Does anyone know the thread size for these holes?

I'm building a Rocket and I'm inclined to use ceramic sockets, any recommendations?

http://angela.com/chinapremiumninepince ... ocket.aspx
http://angela.com/ninepinceramicbottomm ... ocket.aspx

[Smokebreak]

I'm doing a callaham chassis right now and I had to scrounge bottom of my bin but I wanna say 4/40 for those inserts on mine. Yours may be different though. RJ would know of course
Steve at apexjr.com has the ceramics for about $1. I ordered some pots with longer bushings for wooden faceplate from him yesterday at 3p and he shipped them at 5p.