That's the problem, these have been discontinued for so long. Once something is no longer current it vanishes. Human history or a model/part number for a discontinued wheel it's all the same.
Two summers ago a guy offered me a set of 15x8 AR-39's or the Ultra knock offs...but one was missing. He had a different wheel on the fourth tire. As I said earlier I have a soft spot for these so I was considering it. Only problem...I COULD NOT find ONE of those wheels. Found several 3-4 wheel sets for hundreds of dollars but no a single 15x8 6 lug of that style. Finally passed on it and told him good luck finding a 4th.