Been looking for one of these for a while and decided to pounce when the right deal sprang up.
This is a 1986 Marshall JCM 800 50-watt 4010. It began life as a combo amp and the previous owner had a headshell and new faceplate made for the change in orientation.
I've only gotten a small amount of time to play it but the two obvious things are 1.) it sounds fantastic 2.) its loud as a motherfucker (I mean, the knobs go to 11).
I got cleaned out pretty good purchasing it, so it's staying as is for now but this is part of a larger plan I've got in mind. Ideally it'll be getting a Facelift sometime in the next few months.
I haven't gotten a chance to get it on my workbench yet, but I'll get some pictures of the chassis and the guts when I get a chance.