Try Ned at Triode Electronics - www.triodeel.com - 773-871-7459. He shows several types on his web site. You might also search with google with "6DJ8 & tube" and see what turns up. Good luck!
Source For 6DJ8 etc
Can anyone advise a good source for the better/best 6DJ8 and its equivalents. The Amperex 7308 is attractive, but Kevin Deal will not supply anyone outside of the US - or at least that is what he has stated. Are there any other sources that might be more open-minded about their customer base?