The only original battery I have ever seen was on a yellow 1971 240Z with 19,500 miles that was sold in the Seattle area a couple months ago. It was also the Furukawa (see picture). As you know (since you are selling the Yuasa decals on ebay), the parts catalog and service manual pictures show a black Yuasa battery. Nissan may have had more than one supplier or the supplier may have changed at some point. You might get more input on classiczcars.com for a topic like this then on Hybridz.