DennisM,

The Master Parts Book posted by TOCMP (thank you, Keith Hardy) might be a little help?

The series codes are listed on this page.

The COE wheels are not listed for 1940 or for 1946, but it looks like the wheels you are asking about might be different (the 1940 & 1946 standard wheels are different). Even if they are different, they might be interchangeable (in terms of fitting).

Tim