I posted a 992B set of 1950 vintage (C304283) in a brown pull-apart box a while back in this forum. Here is another 992B from 4 years earlier (C154255) in a very similar brown pull-apart box and muslin pouch, with the label taped on with old Scotch tape the same way.

Since we know the ivory plastic flip-top boxes were still in production during this time frame, I think this example lends credence to Terry Hall's theory that the "plain" boxes were a lower cost packaging option for the 992B in the postwar era.

Ed,

This box is the one used for 4992B watches. It is a fabric glued over the cardboard box. It is nothing like the other box you posted. If the labels are taped on it is a "alert" sign to me to proceed with caution.