Hello Gary,

I’m not aware of any specific guide for dating the steel boxes of erector sets. However, a little investigation and research could come close to dating your two set boxes. Greenberg’s Guide to Gilbert Erector Sets would be a great start. Also, on this website under “Erector Set Galleries” there are photos of the sets.

Erector Set Galleries

I would start the investigation with the color of the box. Are they red? For example, beginning in 1947, all of the metal box sets were painted red. Than what label is on the top of the box? Gilbert changed that over the years. Another clue is what is on the inside label? Below is a picture of my 1954 8 1/2 set. As you can see it doesn’t have brass corners.

The early versions like this 1946 and 1947 did have the brass corners.

Notice also the label and blue parts. That’s another clue. Hopefully your sets still have the inside label.

That should at least get you started in your investigation. Let me know if I can help any other way.

Best regards,
Michael