Hi AJ; These are original Gibson Les Paul Jrs
LPJ Example 1 and
LPJ Example 2. Both have single 6V6s, 6" X 9" oval speakers, and speaker-mounted field coil transformers.
For contrast, these are GA5 Skylarks;
SKY Example 1 because the output tube is so skinny, probably either a single 6AQ5 or 6BQ5/EL84 (the model was sold with both),
SKY Example 2 fitted with a single 6V6, and
SKY Example 3; a GA5T fitted with a 6BM8 to provide tremolo which, at the time, none of the other single-ended LP Jrs or Skylarks offered ... although later Skylarks did. The same GA5T circuit was used in Gibson's GA1RT; a remote reverb unit; having owned one, a really fine-sounding amp.
The Skylarks were sold to compete with Fender Champs and 5E2 Princetons; apart from using a resistor in the power supply instead of a choke like the Champ/Princeton, a resistor value here and there, and if the Skylark is fitted with a 6V6, they are the same amps. Strictly speaking, what Gibson re-issued wasn't the Les Paul Jr.; what's out there is the 6BQ5/EL84 version of the Skylark with the Les Paul Jr model name that, for marketing reasons, Gibson scotch-taped to it. The reissues use an EL84, Fungus' GA5 is a 6V6-model Skylark and, beyond the tube type, there's no other useful distinction.
These are single-ended, Class A amps that have their charms; intoxicating tone, simplicity, ease of maintenance, and mojo to burn ... and their limitations; 8 watts tops for power, limited headroom, and in original configuration, usually mated to an 8" speaker. I'm a big fan of the 6V6 but based on the comments of Mad Dog and others more familiar with the EL84, I'd guess the 6V6 is a little warmer, darker, maybe thickish where the EL84 is a little drier, breaks up a little later, and probably more clarity with higher frequencies. CJ