with that nice chrome plating it must be late ‘45 or newer.
Agreed.
...all of mine have the 1945 date codes although the rest of the tools in the sets have the 1944 date code.
Hmm. Interesting observation, Don. I've never thought about this before. My sets are the same.
Just spitballin' here, but maybe they weren't making the TM-10D until 1945? Admittedly, that seems strange at first blush, but I guess it shouldn't surprise us too much given the odd, incremental, almost reluctant way that they introduced 1/4-drive to their production to begin with. As you know, the 1942 catalog did not advertise an entire line of 1/4-drive tools. Just the ratchet, which was the 9/32-drive frame with a 1/4-drive innards plug, previously made available only to Industrial line customers as the GM-70-N. Ostensibly that's why there aren't any "2" tools and very few "3" tools. (I had a 1943 ratchet once, and, like an idiot, sold it with a Snap-on midget set I put inside a GMTK before I realized how rare they were.)
The 1945 catalog shows a full line of TM tools, including a hinge handle, but that was published December 15, 1944.
Maybe it was not an easy tool to make. And there is precedence for that thought, as well. They introduced Midget tools in 1931, but they didn't add the hinge handle until 1937.