Carl,, I did not peek inside,,but knowing Mark,, they are mostl llikely,,pretty heafty trannies,, the tubes on the outside are "voltage regulators",, the signal tubes are 9 pin 12B somethings,,, this thing runs with the big dogs too.!! Hopefully I will own one (after building) at CF this year-- why don't you come on down and stay a wekk or two? You would be in heaven!