Vintage Dahon Stainless Steel Sturmey 3 Speed Folding Bicycle

I haven't located the serial number yet. Even though post reads "Dahon Classic III" I am unsure of the exact model/year. I suspect this is a Hon Convertible - an early model. I will update the post when the serial is found. It is -in my opinion- the more desirable stainless steel version.
Finding and understanding your DAHON’s serial number
One thing we are very proud of at DAHON is how many of our vintage bikes are still out there and in good working order thanks to the care and attention of their owners. Since the very first Hon Convertibles made in 1982 we have produced a number of different frame designs and models. Here we take the opportunity to expand on a common question: How can I find out how old my bike is?
To date your DAHON, the first place to look is on the bottom bracket, by the crank. There you will find the serial number stamped into the frame. If you have a Chinese market model, you will find it on the front of the headset, for some very old Hon Convertibles it may even be etched on a rear chain or seat stay, inside the hinge and sometimes the serial number may be on the upper part of the bottom bracket. The paint is usually applied over the serial number but it should be easy enough to read.
Now you have found your serial number, here is how to decipher those digits:

For the vast majority of DAHONs, the serial number will start with a D (which stands for DAHON and on older models H, for Hon and for a while in the 80s DH) and be followed by about 9 numbers.The first number always indicates the last digit of the year of manufacture. For example D0######## can be 1990, 2000 or 2010. You should be able to tell from the style and model which decade it belongs to. Also note that a ‘2013 model’ bicycle will be manufactured in 2012 and in some cases 2011, as we start on orders as early as possible to get them shipped to various locations around the world. Making the frame is the very first stage in our process.

The second and third numbers refer to the month of manufacture, so D106###### would be June 1991, 2001 or 2011.

Under the current system if there is a letter T after the month, this signifies a steel frame. If it is a 7, then the frame is aluminum.

The remaining numbers then refer to the frame’s number within that run (starting from 00001).

Over the years there have been some other systems and lettering, and our record is sadly not complete. A certain amount of Taiwan made bikes in the 80s will have a serial number starting with A. Chinese market models have a different system. In most cases the year of manufacture is given first as described above, so this is one thing to be confident of.