There is a BB spindle on eBay with hexagonal ends Don't think it's quite the same as yours. But you might finds some hints in it's description to get you started googling for more info.

https://www.ebay.com/itm/284486113024

. However I wouldn't have any issue tossing that one in your bike and putting something more normal in it. Assuming the BB shell matches some standard in common use today. If not, I'd toss the bike to the recycling scrap yard too.