I think I have posted this photo before, but I think you will see some of the knives posted here in this group photo. Note there are three blacks at the top. IIRC, the black 15 and 16 were in there because they had filled bolt holes. Also not the earlier browns were of a lighter shade.

ron might have a better recollection of the model 3 third from the bottom. It had no spacers but was correct I believe. I think it had filled bolt holes also.