69-72 BB Alternator bracket difference questions

[Mr70]

I agree with most of what has been said.
My October '69 Leeds assembled 1970 Chevelle originally came w/the top Alt.bkt. shown on the far right,and with the the negative battery cable grounded to the block,not to the bkt.with a star washer under it digging in.
And the designated hole for it was never tapped.
Nearly every top bkt.I see,has that hole tapped and you can see where the star washer bit into it,leaving a noticeable impression.

I think I have a 1970 production service bulletin stating the battery should now be grounded to that top Alt. bkt.,not the block like in '69,but there seems to be a few early '70 assembles that didn't pay attention,or get the memo in time.

[RPOL88]

Do all factory bottom brackets have markings on them or were some without?