Screw Chek'rs, for having printed letters and numbers, not stamped or engraved.
Same thing with newer electrical multi pliers!
The older ones were stamped or engraved.
I've got one of these jacks too. I bought it new, in Sears, White Plains, NY. I'm thinking 1980.
It's been fantastic--I never had any problem with it, never had to add any oil. I've only cleaned it off from time to time. Greased the saddle post, and oiled the casters, that's been it...