Thanks for the links, going by that info I'm assuming all the ones I have were made after the 1970s. Here's a pic of the three variations I have making up my SAE set. The middle one is definitely the newest seeing as that's how they look now, it's the other two that I don't know about. It's kind of odd how the top wrench is stamped on opposite sides of the wrench from the other two.
Generally, S hyphen K is prior to 1985 (when FACOM took them over). It then changed to S dot K or S circle K. When SK split from FACOM in 2005, they kept the S circle K stamp.
They only way I can (sort of) tell FACOM-era SK from Independent SK (on wrenches) is the broaching. It appears that SK introduced Sure-Grip (their flank drive style) broaching on their wrenches in 2004 - right before leaving FACOM.
Now, your two older wrenches. The SK items I have from the early 80's were marked S-K TOOLS. Dresser Industries bought SK from Wayne in 1969, then sold out to FACOM in 1985. I don't know when they changed from S-K to S-K TOOLS, but they had by 1981.
Hope this helps.
