Cameron,
Regarding the first pair of amplifiers, I looked up the (potential) power output of two 6L6 tubes running 'push-pull' in the 1953 Radio Amateur's Handbook. If the circuitry is Class A, the output power will be around 18.5 watts. If run as Class AB amplifiers, depending on the circuitry and bias, each amplifier might put out between 24.5 and 47 watts. The 6L6 was a very popular tube and spares should be readily available. Have you looked under the chassis to see if there is any identifying information?
Jim
PS I went thru the advertisments in the 1953 book mentioned above and the audio amplifiers available are all built on a single chassis, with the exception of a Heathkit model. That suggests to me your first pictured amplifier pre-dates 1953. I'll forward your photos to a friend in his late 70s who may be able to identfy it.