Note that, while S Scale Locomotive & Supply is no longer in business, these documents provide a wealth of information about the parts that make up a steam locomotive. According to Dick Karnes, the "first edition" of the SSL&S catalog was a set of mimeographed sheets. The "second edition" was the red book, and "third edition" was the blue book. A lot of companies back then weren't fastidious about putting copyright years on their materials, so it is unknown as to exactly in which years these came out. The physical media NASG Library (as managed by Dave Jasper) has hard copies of these catalogs, should you need access to them.
"Red Book" Catalog (scanned by Bill Roberts)
Third Edition "Blue Book" Catalog (scanned by Chris Rooney)
Third Edition Parts Installation (scanned by Chris Rooney)