OEM-style battery cables for slant 6?
Are you talking about a split, do you mean a terminal like this?
At least on the late 60s cars, this is the connection to the starter relay, and I think the otehr end was a ring terminal. Wire itself should be brown (this reproduction is black - incorrect)
probably the original from my '67
That wire was bundled with the starter cable from the battery.
This is a little more correct in that respect.
FWIW 1969 6 cyl cable routing