Definitely no older than mid-60's and it might even be as young as the early 70's. Sears/Silvertone is a good possibility, or maybe a Lafayette with different grille cloth.
The early transistor amps (they didn't start mass-marketing transistor amps until roughly the mid 60's) were not particularly good, and if it has any sort of problems at all, those early transistors are unobtainable. Personally I would only take it if they gave it to me...maybe...but I've got more amp projects than I know what to do with.
Expect to have to completely re-cap it--those 50 year old electrolytic caps are well past their life span. Then "enjoy" its low power and odd-harmonic distortion when driven hard.