There's got to be a marking or serial number somewhere. Where did you get it from? Are you going to run it? I'm not sure when clip meters started showing up on amps but that should give you an idea of how old it is. Does it have a bass knob? I believe Coolhand in saying that it is a mono amp. And I've never agreed with @Coolhand20th on this. I've never agreed with him on anything. Just kidding, we battle but agree sometimes.