I just checked my copy of the 25 June 1945 dated SNL G-85 Vol. IV and G506. It have an exhaustive list of model numbers, which include numbers in the 4100 range (ie. 4112, 4103. etc) and also numbers in the 7100 range (ie. 7106, 7107, 7116, 7105, etc.) I found no mention of any 7500 range of...