Great thread and great info. Got my 110 from my dad back in 1976 I'm thinking. Just looked and it has two dots. One on each side of the 110 stamp. Still have the black leather sheath and do carry it every now and then for old times sake.
The date of manufacture of your two dot from around 1976 could be nailed down better by the number of handle pins and their size.
Earlier manufacture (1974-1975) could have just two small pins and the rocker bar rivet.
In about 1976 Buck was in another transition with the two dots and added two more small rear handle pins. They used all the holes in the sintered brass frame for a short while which ended up giving the knife four small handle pins and the rocker rivet.
The in late 1976 (about) and through 1977, Buck used three small handle pins and the rocker rivet.
A lot of those 110s with the three small handle pins still had the hole for the fourth pin in the frame, but it was not used.
The 1978-1979 two dot 110s have three larger handle pins and the rocker rivet.
Then came the three dots after that.
Always remember that the years are approximate as manufacture changes at Buck are done at any time during the year, not just at the start of the year.
Those older leather sheaths rode nice and low on the belt. My favorite of all the 110 sheaths made.
I have pretty much given up on the belt sheaths for 110 carry now and gone just about exclusively to pocket clip carry. (I add my own pocket clips)
That one thing made a huge difference for me in the amount of time I carry a 110. I LOVE the pocket clips and the 110 carries very well that way.