this assembly holds a floating tool holder that has a 1 3/8 inch "automotive" shank - it's called a "max float" holder - the holder has a 3 MT female taper that floats laterally.  The steel bracket holds the holder at lathe center height and rides on the same ways that the tailstock rides on.  I still need to attach the #3 MT to the tail end of it so  that it will be aligned and moved by the tailstock.  For tapping, put this in front of the tailstock, and put the tap into the floating holder using a 3 MT tap holder - then advance until the tap starts to cut - the tap will pull the holder forward as it cuts, and the torque is taken up by a woodruf key on the floating holder that transfers the torque to the steel assembly.  It also still needs paint.  I don't think I will need a clamp to hold it to the ways, the tailstock and the cutting tool itself should do the trick.