1938-1942. We know this has to be 1938 or after from the "more than ninety years" under the address. This continued into at least part of 1942. This variant was included along with a note about a war time shortage of nickel. With about 4-1/2 years of usage this one is fairly common. (And may have different paper colors.)
Late 1942 or early 1943. The biggest change in this reprinting is "Pink the baby's diapers. It is better than hemming because it eliminates bumpy seams which hurt his soft skin." Other differences: the heading in the upper right was split into two rows and at the bottom under the address the font was squeezed to get the first to fit onto one row.
1944. Postal Zones were introduced in 1943, and after they used up the prior printing, they reprinted with 7 added to the address. The second paragraph now mentions the Model A. And instruction #2 dropped 3-in-1 oil as an alternative.
c1946-1947. Numerous small changes. The back also changed to add the Model A pinking shears, which is noted here in the first paragraph and above the address. Along with this reprinting they started printing a Model A instructions. Around this time they changed the design of the Model A and its new box now allowed for including an instructions.
1948-1949. In 1948 they added the year and 100 years. This was used until the first few months of 1950 when they switched the instructions to a multi-page folder. Those can be found on the 1950s page.