Everybody's welcome. I'm glad to have a chance to put my tube knowledge to use. Another good resource is Brent Jessee's web site:
He has the Telefunken tube codes there as well as explanations of all the tube varieties that can be substituted for a particular tube like the 12AU7. He also gives opinions on the sound of various tubes, some pretty specific, some general. These opinions aren't gospel. You never really know how a tube will sound in your system until you plug it in and listen. He has a good reputation as a tube dealer and he'll help you find what you want if you give him a call.