thanks memzey - there are two oddities there, the first and the third vice. Are you sure the screw and nut covers have not fallen off and got lost under your bench?!
Seriously, you must be right that at some point the makers offered a 'square boss' version without the cover.
I do think it was a reintroduction though, based on the B&H catalogue below (1971). Unfortunately this is the latest catalogue I can find - perhaps the 53 (no prefix) was introduced after the Record/Ridgway merger (1972) ? Does anyone have a catalogue from this era?
I can't explain the 53A - all the catalogues pre 1963 agree that 'A' = with screw and nut cover. Is there a small hole on the inside of the front jaw above the screw where a cover might have been attached?
Seriously, you must be right that at some point the makers offered a 'square boss' version without the cover.
I do think it was a reintroduction though, based on the B&H catalogue below (1971). Unfortunately this is the latest catalogue I can find - perhaps the 53 (no prefix) was introduced after the Record/Ridgway merger (1972) ? Does anyone have a catalogue from this era?
I can't explain the 53A - all the catalogues pre 1963 agree that 'A' = with screw and nut cover. Is there a small hole on the inside of the front jaw above the screw where a cover might have been attached?