Two 6L6 power tubes. Mark Stephenson re-built mine, and it will accept two EL34 instead if preferred. I have not tried that, and have no intentions at this time. Still, a nice option.
Gar told me less than two dozen built when I dropped it off, and just over a dozen when I picked it up. Lets call it a dozen and a half.
My speakers were not "upgrades", but in fact are Jensen square magnet full-range vocal speakers for PA. They sound good, but I prefer a couple of Vintage 30's that I have.
The 70W power rating is an overstatement I think, although I did donate to Gar's friend a theatre amp that was rated 150w with two HUGE 6L6, so you techies can argue about that if you like. The amp is too loud to use on the Overdrive circuit, but sounds glorious if you were thinking of giving up on hearing anyway. I set it at less than one for a crunchie alternative to the amps beautiful cleans. Also adds some real meat to a pedal distortion, which I have done in the past, but not at this time. I would like to try Gar's Guillotine with this amp.
Again, all this and much, much more can be found in the Traynor Garnet thread.