Here is my Guild Aristocrat / M-75 / Bluesbird guitar. I think it is a 1956 model but I'm guessing based on a picture that I saw of a '56 model with a bridge the same as the original bridge on this one. There is no obvious serial number. There may be something inside under the pickup. I bought this guitar in the mid-60's and I've had it ever since.
I never thought of it as anything particularly special or as a potential museum piece so I felt quite free to make whatever changes appealed to me at the time. It was originally a sunburst finish with a dark mahogany back and neck but I didn't like the look of it very much so at some point I decided that it had to be black. I did an ok job and the finish has lasted pretty well. At some point I may decide that it needs a real fancy finish but for now I'm still happy with it.
The soap bar at the neck is the original. As you can see, I replaced the other one with a humbucker with its own 2-way switch. That was quite a while back so I don't remember who the manufacturer was. I took off the original tuning pegs (one was bent) and bought some replacements. I'm thinking of getting some gold ones as these ones are chrome and don't quite match.
As you can see, the bridge isn't the original rosewood. I couldn't get the touch to where I wanted it with the original bridge so I got a piece of chrome, mounted it on the feet from the original bridge and cut some slots for the strings. It's painted gold to fit in better. I've been looking at the gibson-style bridges with the rollers and thinking that I might give that a try. It has some Guild knobs that I bought on Ebay. The originals were clear plastic. These look better with the black paint.
Here's a shot with the case. I'm pretty sure that it is the original. It's kind of a heavy cardboard with a leathertte finish. The handle is plastic. So with all the modifications, it probably isn't worth nearly as much as if I had left it alone but I'm happy with it and I've had it so long, I'm not interested in selling 
anyway.