Dating supro logos
Also they did use some old parts on early newer generation guitars.
Parts as control knobs, screws and especially tuning machines seem to have been put on these guitars as they came available...
Check the string attach, but remember that the late 1950's models had "string-thru-the-body" attach too (but won't have the integrated bridge).
Even some late post-war model may have left the factory with an impressive 1-1/5" pu (I haven't seen one yet, but after all I have seen, it wouldn't surprise me).
I am in the process of collecting digital photos of B and A series Rickenbacher lap steels and all information (catalog copies) possible. Remember that there were Rickenbachers built after the war with mixed parts like pre war bodies and name plates combined with after war pickups.
If you can take pictures of your guitar(s) please e-mail them to me together with serial number info. I have played one of these and it really had the that people want in these bakelites. Everything about it says "pre-August 37," except that there are two control knobs on the right cover plate. ------------------ Herb's Steel Guitar Pages Texas Steel Guitar Association Great job JD.
Earliest models may have no mention of any US-patent of metallic parts. You have to understand that bakelite is a very hard and abrasive to machine material, requiring tool to be re-sharpened very, very often.