Mark Levinson - what have I bought?

I have purchased an early Mark Levinson Preamplifier/Mixer with no model number on it - pre production model. I know that ML made some mixers for Joan Baez biography movie and also a mixer fore Woodstock as well. I also know that his first production line was the famous LNP-2 preamplifier.  Is it possible that I've got the LNP-1 preamplifier or one of the four early mixers he made in the 1970's?  Your help will be greatly appreciated. Thank you.
This unit has 2 large UV meters on the front panel: it is two channel stereo as well as option four channel also: it has four volume pots and four panning pads; one master fader knob; one select knob for mono, off and tape. All the inputs and outputs are XLR connectors. Inside, there are two Burwen amplifiers, and two Burwen Meter limiter units as well. 

Have it looked over by a qualified tech.

 Sounds like a great acquisition to your rack!
This is the exact ML rack mounting mixer/preamplifier I purchased, and this is the only picture on the web.  Even, ML side doesn't have a picture of it on their web side.  I also don't see anywhere pictures of LNP-1 preamplifier.  So far, I have been given an advise that only the man who design it will be able to tell me what I've got.   Any ideas?                     

This is a microphone mixer, made for the Pro market, not home hi-fi. David Manley did the same, one studio I was in having a Manley mic pre-amp (tube, of course). 
The following is from an interview with Mark Levinson himself. 

 “I was hired to do some recording for a film about Joan Baez; it was my job to spec the equipment. I learned that the only portable mixer at the time was made by Nagra, but it clipped very easily. We had Neumann condenser microphones on Joan and the other musicians, and the inputs on the mixer would overload all the time. And I thought maybe something should be done about this.

“In those days, film sound was really about dialog, not high-quality music on location. I realized there was a need for something, and around the same time, I was introduced to Dick Burwen, a real scientist and engineer with a tremendously deep background. Dick was willing to mentor me, and our first project was making a mixer for the Baez film. I did the design and he built the modules. He mentored me on how to make something work well.

“We built four of them before we realized that film professionals were not willing to pay for quality; as long as sound came out, that was good enough. So there wasn’t much of a path there. At one point, one of our associates said, ‘While we’re thinking about what to do next, can we listen to some music?’ And I said, ‘Well, we need a preamp. Why don’t we make one? We have these modules sitting around.’ So I called Dick and asked if we could build a preamp, and he agreed.

“That unit, which I called the LNP-1 for ‘low-noise preamp,’ ended up on a shelf in my parents’ home. A guy came by who was going to buy a pair of speakers I had, and he asked to hear it. So I played the system, and he said, ‘Wow, that’s amazing! Do you know how many people would want to buy this thing?’ I started thinking that I might be able to make some money. That was the impetus to develop the LNP-2 in 1972 under the Mark Levinson brand, which became an audiophile classic.”

So, the question is, how likely is that this microphone preamplifier is one of the only four made by ML and how can one be sure of that?