The black ones were used on Sunburst Models from 1952 through sometime in 1954. My understanding was that the black ones were phased out completely by the beginning of 1955. Being that the T100 didn't come into existence until 1958 I would think they would not be original to the Guitar but I am sure there are always exceptions to the rule. If you get a chance to pickup Hans's Book "The Guild Guitar Book:The Company and It's Instruments. 1952-1977" I would highly recommend it. That is pretty much the Bible on all things Guild from the beginning up until 1977 and it has the correct info in it. I just don't have access to my copy right now so I am going off of Memory. Hope this helps!
TX