The Balanced ECC83S is located in V7 closest to the power tubes and the two ECC81's are located in V4 and V5.All 6L6GC Combo amp Retube Kits are shipped with the Eurotubes Double Mica 6L6GC’s at no extra charge. JJ Electronic started building us a proprietary version of their 6L6GC (the 6L6GC-DM) in 2005 with extra layers of mica. This reinforces the plate structure and all but eliminates tube rattle symptoms. For all other tubes such as 5881's, EL34’s, EL34II’s, E34L’s, KT77’s and 6CA7’s we recommend using our EuroDamper rings. These are available under the "Related Products” tab as a pair.