I had bought an old Marshall head and cabinet from its original owner for $200 back in the late 80's/early 90's. He said it was just sitting in his garage getting dusty..., not sure if it worked..., I only played guitar for a short time..., have no idea what these old tube amps are worth, etc.
I really didn't either, but I wasn't about to educate him; I knew 2 hundred was a bit of a steal, but the cab was in rough shape. But it was a 4x12 with 25 watt Greenbacks, so I didn't really care what it looked like.
I used it as half of my stereo rig for a few years, until I heard about this amp called MP-1, which I had to have. But this Marshall had no MV, and it just wasn't working for me with the ADA MP-1. So I traded it and my JCM 900 head for a new Mesa Stereo 50/50, and was happier than the proverbial pig-in-sh!t!
I didn't realize what I'd had until later, but it was either a JTM or JMP, the old style with the small script. I wanna say it was a JTM 45. Either way, I was happy because I got the tone, and control over it that I wanted, but I'm pretty sure the sales mgr at GC did a little dance after I left.