I have now found this tubes here in sweden, Sylvania 5751WA whit CBS logo, triple mica, O-getter, grey plates from 1963 and Sylvania GB5751WA gold brand (pics under on gold brand) Is the gold brand the right tube ? it looks like triple mica but is it gray or black plates?
http://www.bilddump.se/bilder/201910....44.150.61.jpg