6 volt battery cable guage?9

I have read on an older Chevy site that 2/0 (00) or 4/0 (0000) gage was used on 6 volt Chevys. www.batterycablesusa.com makes them to size.
The OEM ones were never that large except maybe heavy trucks. I always thought they were simply 1 gauge.

Some of the "modern" so called "parts stores" don't even carry those