However, when it arrived I noticed a few subtleties that made me rethink things. I posted it to a the Vintage Watch Forum, and one of my forum mates identified it as a 1967 M69-4.
That was very interesting in a couple of ways. First, I didn't know Hamilton made M-series watches in any years other than 1964. Second, I found out there are other resources out there to help identify watches. There are a number of "mystery watches" and perhaps we'll someday collect enough reference materials to be able to formally identify them.
Anyway, the M69-4 looks a lot like a 1965 Dateline S-575 that I've also posted about. Tucked inside the stainless steel case is a Hamilton 688 Swiss-made movement. The white dial has a radial finish with silver-colored numerals and markers.
Since I thought the watch was a M69-2, I wasn't planning on posting about it. So I didn't take any "before" shots. It arrived in typical project-watch condition - rather beat up, dirty, and in this case it wasn't working either.
Fortunately, all it really needed was a thorough cleaning and a new crystal to look "good as new".
You can compare the photo above to the Dateline S-575 below. They are almost identical except for the date window at the 3 position and the vertical and horizontal lines on the dial.