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

OK,I did a fair amount of searching,and haven't found an answer to this.....
are the 170 LG blocks made in '68-'70 5 core holes like the RG blocks? The castings were
changed together earlier in the '64 era with the 5th digit of the casting numbers being the
only difference ( -2- for the LG and -4- for the RG), but I can find no listing for a parallel
casting change later. CarrlieS ?? Anyone? If there is, I would like to obtain one next
springtime, I have acquired a '62 and a '64, both 3 core hole versions of course.
I have been to the .org site w/the casting list BTW, and they state that they
know the list is not complete,so lets try to fill in the gaps!!THX :coffee2: