Bulova 1928 Juno

I cannot find a date code.  The closest thing to a date code I can find is like a capitol D lying on it's back, so it looks like a mound.  I cannot find that symbol listed as a date code.  I chose 1924 for the manufacture year on this form because an entry is required and that is the patent date but I do not know the actual year of manufacture.  On the outer edge of the movement above the largest gear are the words "FIFTEEN JEWELS".  There appears to be something written to the left of that but I cannot make it out.  On the inside of the case, above what I believe to be the case serial number (8142315) there is another number etched in the metal.  It appears that someone scratched it in by hand.  I think it is "C6734G" but I may have one or both of the letters at the beginning and end wrong.  a line extends from the last letter and loops back to underline the number then curves down, finishing like a J turned backwards and tilted to the right.  It kind of resembles the Barbara, but the design on the case is not right.  Thanks in advance for any help you can provide with identifying this watch.