Was going back through this thread in order to answer questions for someone else regarding -6AN lines and adapters, and I realized that for some reason I never typed in the part number for the Vibrant Performance 5/8"-18 inverted flare to -6AN adapters that I used for the radiator transmission cooler fittings. It's 16436.
https://www.summitracing.com/parts/vpe-16436
https://www.summitracing.com/parts/vpe-16436