Ok I have a 1971-73 50 watt JMP NMV head. Old style knobs, 4 input. Window OHM selector. The back has been replaced with just a metal grate I bought it that way. Its made in England and has been modded for American power I assume. I got it for a great price and it sounds killer came with NOS Mullard El34s too. I do not have it here its at my drummers house so yes a pic would be helpful I'm sure. However is there a way to tell via the serial number? Or any other trick, its the only vintage Marshall I own so I'm at as familiar with it as say old Super Reverbs. It sounds ****ing killer instead of buying a "boutique" copy that wil have things I do not want (ie effects loop, master volume, high low gain inputs) and loose its value as soon as I purchase it. Anyways I collect amps and I'm curious what she is besides a kick ass blues rock n roll amp. Thanks.