Dave doesn't know either.
Several years ago I was in CA on a business trip, so I stopped by his shop to pay him a visit. We chatted for a while. In the conversation I mentioned that I was the person who discovered the lower ball joint replacement. He reaction was very neutral, which I read to be he didn't like the idea that someone had come up with a replacement. The irony is that he only had 4 left and had stated that he was not able to purchase any more from his source. My gut feeling is that he was sourcing this from the same source as the OEM, rather than buying a known part for an XYZ vehicle. So those sources may be completely dried up anyway.
But in the end, there has to be a truck part somewhere that matches up. No one is going to pay the cost to have one custom made. That does not make sense. I would be inclined to also look at some agricultural sources as well. Here is just one source that provides dimensions:
https://qualityfarmsupply.com/collections/tie-rod-endsNot sure if anything fits, but it would be a place to start. There are several options that are 1 inch diameter threads, so it is very likely there will be something within those 13 pages that will match up. Make sure to pay attention to LH or RH threads. Revcon used both, depending on location.