I always liked green labeled Sylvania 6L6GC tubes when I had an amp that used the 6L6 type tubes.
For new tubes I say try the Sovtek.
http://www.dougstubes.com/power-tubes/6l6-5881-kt66.html
For new tubes I say try the Sovtek.
http://www.dougstubes.com/power-tubes/6l6-5881-kt66.html