Doug, thanks for the repsonse. This was the first time I have ever had two of the exact same sample before and thought it interesting. To me, the chip with the 3 half circle notches looks to have been machined but the chip with the four notches looks to have been notched with a hand tool similar to a tile nipper or other similr tool due to the rough nature of the notches. I find it interesting as I imagined the exact same chip samples were all made at the same time. Begs the question, were they notched straight away or notched at a later date when needed before leaving with the salesman etc. I don't profess to have any idea I am merely speculating as I find it a little curious.

And no I will add an additional question. Any idea on dates of manufacture between the two different styled backs?