clang, you're NOT alone!
I just purchased this fine S&W Model 10-1 Heavy 4" Barrel that is also showing "Mod - 101" on the frame at a gun show on the 15th of this month!
It is S/N C521XXX (about 1961 vintage) and I got it OTD for $285. It's as solid as new on all tests, such as inspection, endshake, timing, push-off, etc. And I'd rate the the bluing at about 98%. I did a detail strip and all is perfect inside - just some grease added by the former owner, but I cleaned it and oiled it with FP-10 instead.
Here are some Pics I took to give some idea of what I have here:
The grips that came with it had the correct S/N on the inner surface of the right side grip and are
exactly the same style as the grips shown here, but had some noticable wear, so (as I had this set of
NEW condition diamond magnas) I put these on and stored the originals in a plastic bag to stay with the gun for posterity. I like the crisp new look of these grips for show better!
(Did I do well?)
I'd like to read your comments
RonJon