Set 704C (above) includes a mini-MMM Moon Crawler, which would date this series to well after 1966 when the Crawler was first introduced by Mattel. The "C" in the set number is in black only, making it cheaper to change to another letter when printing boxes.
5 1/2 in
4 3/8 in
Set 704A (above) has a cyan-blue base colour as opposed to the brownish red of set 704C at top. This is simpler to print so might be a later development.
Each of these sets came with a rocket, three astronaut figures and one other vehicle that differed from set to set. All are glued to the box insert.
Box flaps have identical illustration - box rear is mostly blank.