A good example of a tough model to identify is the 1961 M 59-1. As you can see by the name, it's a men's model priced at $59 and it was the first M-series model at that price.
I don't have a catalog snip for the model (yet) but I have it on good authority that my project watch is an M 59-1. It has a very familiar dial with a distinctively shaped numeral 4 and concentric rings around the numerals and markers.
I knew the dial looked familiar and I realized it's very similar to the 1960 Thinline 5000. I happened to have a Thinline 5000 project watch waiting it's turn at the spa so I can compare the two models directly. You can't see in the photo but the crystal is a bit scratched up and it looks like the I in Hamilton is missing. It's actually there, as you'll see later.
The M 59-1 has a two piece case with a 10K RGP bezel and a pop-off stainless steel back.
The Thinline 5000 has a one-piece case and opens through the crystal.
The Kreisler bracelet on the M 59-1 appears to be original and it's in decent condition but very dirty. We'll have to see what it looks like after it's cleaned.
The dial finish on both of my project watches leaves a little to be desired. The M 59-1 is a little compromised from the 2 around the 6 and up to 10. From 11 to 1 it looks like it should. I don't know if there's just some funk on the dial or if the finish itself is impacted. I suspect the latter.
There's a Hamilton 673 movement behind the dial. That's different than the Thinline 5000 - it has a very similar, but thinner, Hamilton 676.
I can tell from the inside of the case back that this watch has been to a watchmaker at least twice in the last 50+ years. It's arguably long over due for a cleaning.
The M 59-1 has a very low profile and a sub second hand so I will try a 30.1mm PK low profile crystal. It will look sharp as long as the minute hand doesn't rub it. Otherwise I'll go with a PHD high dome crystal.
The reassembled movement is ticking away with good motion. That's a promising sign.
A slight tweak to the regulator is all this watch needs to keep perfect time.
I treated the dial to a "poor man's refinish", meaning I cleaned it and sprayed it with a light coat of clear lacquer. It's definitely not perfect but it is a nice looking watch, especially from more that a foot or so away. The bracelet cleaned up great a most of the marks you see are just reflections.
And for direct comparison, here are the two project watches side by side. The Thineline 5000 has luminous hands and markers. The font on the dial is different with the M 59-1 featuring the new stylized H logo that Hamilton lifted from their acquisition of Huguenin Watch Company in March of 1959. (Notice the "I" in Hamilton on the Thinline has magically reappeared) The shape of the lugs is obviously different between models. The dials look almost identical although the shape of the 6 might be different. Lastly, the Thinline has a slightly larger crystal by about 1mm.
Overall they're a nice looking pair of watches. Don't you agree?