anyone ever use one?

http://store.summitracing.com/partde...50+4294924755+

 

People quit using them years ago because of issues with aged transmissions. All it does is increase the transmission line pressure which some don't handle too well. On your 1955 Z, you could add a trans performance mode button and make use of those tables that provide firmer shifts (or you could customize the tables to your liking, leaving you the option of switching between the modes).