Read up a bit more on the old Marshalls and discovered I actually had one of the early JMP Metal Panel ones from '69 onwards so it may have been early to mid '70s. Bought it second hand with a new Wasp slant front quad box fitted with 4 x 12" Greenbacks for $950 early 1980 and that same rig would be worth at least 3 - 4 times more today. It is the rig shown in a couple of the prior photos. Nothing beats the feeling that comes from the sound pressure of a seriously cranked one of these as you can actually feel the chords as you played and the mid range feedback was to die for. Had to use a Boss Overdrive Pedal for gain control as these required way too much volume before suitable distortion arrived unless you wanted to sound like Angus Young with plenty of volume and just a slight amount of edgy gain driven distortion which was very much 'the sound' back in early 1970's.