Just picked up my second silverface bassman. My first one has been serviced and a few small mods done to the tone stack. Both are 1971-1973 models. It is interesting to note that there are several circuit differences between them. The newest one had small caps on V1A and V2A plate resistors which my old one did not, also the phase inverter on the new one had completely different resistor values. I basically have taken the new one and backdated it to resemble more of a Blackface model also changed the tone coupling caps on the bass channel to 0.022 mallorys. In my opinion these amps are the unsung heroes of the vintage amp world. Picked my first one up for 475 and the newest one for 425. Hard to beat that for 50 watt all tube amp with serious iron.