You can still get the alternator that Matt was referring to. I'm not sure why Matt at first called it "custom", and then claimed it was in a "custom case" because the "black beast" that was in Matt's photo and video looks precisely like a standard off the shelf Prestolite / Leece-Neville AVi1602002-2 in the same case that it has always been available in as a commercial duty Ford replacement 230 amp alternator that Leece-Neville has offered since 2009.
That's why I asked Matt what he meant by "custom", because he said "I am working on some custom alternators" but then presented the AVi1602002-2.
I'm shopping for a couple of good alternators too... with low cut in amperage and high thermal capacity. The trouble with the high dollar Mechman and DC Power Engineering Inc 370 amp alternators is that the high amperage rating has a higher cut in... producing less amperage at idle than similar hairpin designs from the same two companies that have a lower amperage rating, like the 240A, as an example.