The "Tweed" era of Gibson only covers a short period between '59-'61, and many believe these are some of the best amps they ever produced. They certainly have a distinct sound and live up to the Tweed sound, comparable to Fender amps of the era, but at a fraction of the price. This amp in particular was used in the J. Geils band, and was purchased from the Skinner auction house.
Internally, it has a changed power cord and electrolytic caps, along with a couple of power resistors. Otherwise the circuit is original. Also, the changed Eminence speakers do a great job of preserving an authentic vintage sound!