Do you still have the old one?
I would try to build my own pack. It looks like they were carbon-zinc. You could use three Alkaline or even nimh of whatever fit, and wire them in series. I can’t find dimensions for them, but my guess is 3xAA.
I have the old ones and want to revive.I consider them very good flashlights in terms of durability and simplicity (no circuits, no leds ). their bulbs can be found easily and regarding battery probably a DIY pack is the option