I have a Circle D, and it's awesome. Heard great things about Yank. These 2 companies are actually making custom converters. Companies like TCI modify old 4 cylinder converters to make them work, and you end up with things like a really small lock-up clutch, and it's just much better to spend the extra money on a much nicer unit. I would honestly have to look up more info for a more detailed desciption, but you do get what you pay for.