Does anybody know of an electrical identification manual for products used in our industry like conduit bodies, j-boxes etc.

If one exists, it would be UL's. If you had enough money (you don't, NO one does) you could probably purchase it. The best is to get a Raco catalog, Carlon catalog, etc. The materials are listed in there with their UL ratings. Pictures of most of these things are in the American Electricians Handbook, or something like Stallcups "Designing Electrical Systems" (may have mis spoke there, I think Jim gave that up this year)

Other catalogs such as Crouse-Hinds, Square D, Appleton, Killark, Houston Wire and Cable, Annixter Wire and Cable, Bussmann, Belden wire and cable, Hubbell, just to name a few good ones to have on hand. Your local Graybar supplier should have a catalog, as does Grainger. Many of these catalogs will give dimensions of boxes, panel cans, etc. for your planning installations. We, in the design end of this business, depend on catalogs information all the time to do necessary details for the installation contractors. Most of these same catalogs are out here on the internet, with email contacts if you need additional information.
Hope this helps.

About five years back I picked up a book titled "Handbook of Electrical Construction Tools and Materials" by Gene Whitson, printed by McGraw-Hill; ISBN 0-07-069920-8. It is one third tools, two thirds material. General overview of each kind of thing.