'68 thru '70 170 blocks...5 core holes?

I have seven 170 blocks. All are 3 freeze plug units.
2463230-7
2202843-8
2463230-2
2463230-8
2463230-1 deck stamping cc 170 11 02
2463230-3 deck stamping B 170 05 21
last one is where I can't read anything, but I know it is no later then 1965