All photos and information thanks to Andrew Edgcombe.

Both cases shown on the right and below are have December 1941 filling/packing date, lot 83 from Ford Motor Company Wellington NZ.
Note the box with Hand ánd Rifle information stating it includes grenade launching blanks. Later boxes were Handgrenade only.
The other box has been reinspected later in its service life (1957)and been changed to Hand grenade only by painting over the rifle grenade references.

Photos below : These show the lid sealing tapes, one N Z with Broad Arrow and one FM NZ (Ford Motors).
The right photo belongs to the 1942 box shown below it.

Ford Motor Company February 1942, lot 16.

The Ford boxes were constructed on-site at the Ford Motor Co Wellington.

Inside of the 1942 lid :