M60 bottom end question

[Jean]

While inspecting two m60 blocks for differences, I noticed these marks on both, what do these signify?

My 93 block has 2 1 2 1 1 and the 95 blocks has 2 2 1 1 1, I've read something about main bearing identification by color, but what is this?

0617 = 1995 block
0638/39/40 = 1994 block

[Jean]

And another difference -
1995 block has B40 180/0 180/0 at the top/rear by the firewall
file 0606

1993 block does not have anything stamped in that spot?
file 0587


Casting part numbers on the side of the block =
1993 block has 0180/1 1 725 963h = nikasil
1995 block 180/0 1 742 998i = nikasil