This is the Standard Retube Kit for the Mesa 290 Power Amp. The preamp section uses three Matched and Balanced ECC83S's. The default power tubes are a matched octet of the JJ Electronic 6L6GC’s. With the customize option you can configure this kit to use a matched quad of the 6L6GC along with a matched quad the JJ EL34’s, E34L's, EL34II's, KT77’s or Big Bottle 6CA7’s. Checkout the additional images up top for the correct placement of the 6L6GC's depending on whether you have the version One (Blue pilot light) or the version Two (Red pilot light.)
These amps are fixed bias with no adjustment. The 290 is a Simuclass amp and can run a quad of 6L6GC's along with a quad of EL34's, E34L's, KT77's and 6CA7's. Please see the addition views which explain where to run the tubes depending on which version you have.