D/P The base looks nice, and that's a good photo you've provided which leads me to yet one more thought about dating this phone. My guess is that sometime between the 1948 sets and the 1949 test models, the base plate stamping was changed from what you have to what we see in 1950,51, etc....but possibly later, in 1949 ? It seems that this is among the more noticeable modifications with the 48-50 sets. Kind of wonder why WE did this since after reading notes on field test models, every one was very satisfied with appearance and performance, and it seems that the size of the base and the placement of components did not change, although how the feet are mounted changed, as discussed earlier in this thread. I think at some point, that number 125 stamped on your base will be tied to some Bell Lab notes on the 500 and will specifically date the phone and where it was tested. I would think there are notes on every one of the 4,000 1949 sets since they also sent out a 302 to be exchanged and compared with the 500 (same household)......thats just how detailed Bell Labs and WE were.
Also; Is there a U.S. Patent on the design of the 500 and what was the date it was filed.. Design Patents numbers are preceded by the letter D. For a second I thought that the number on this set, D177001 was the design Patent, but that number dates to 1956, so it's not a design Patent number.
Something tells me this will be among the longest threads the forum has seen ....
Drew