For the purpose of changing wheels, Datsun 1200s were equipped with an easy-to-use scissor-type Jack. It shipped in the boot, as shown in the Owners' manual.
USA 1972 Owners manual (see page 27 for details):
First apply the parking brakes...
Jack-up the 1200 at these points:
Using OEM jack (see Owners Manual above):
- under rocker panel front
- under rocker panel rear
Be sure to use an old-school Nissan or Toyota jack with a "slot" to fit over the rocker panel seam.
To remove the lugnuts, you may stand on the wheel wrench. But don't stand on it to tighten -- they should not be tightened too much to avoid breaking the lugs or warping the brakes. Only tighten the lugnuts using your hands on the wrench.
Tighten in the pattern shown in the Owner's manual
Remove by turning anti-clockwise. Tighten clockwise. Remember: "Righty-tighty, lefty-loosey".
CAUTION: Don't be tempted to stick your head under the car, unless you fit jackstands (safety stands) to the car first.