When you put 73 up disc brakes on a pre 73 vehicle, a prepackaged "kit" gets complicated. This brake change has been done sooo many times that these vendors probably can put together a kit with all the correct parts you need. I don't know for sure. I only know that if you keep the pre 73 center link, pitman and idler arms, parts in a 73 up kit wont work. If you'll keep the pre 73 upper control arms with small ball joints, you'll need adapters for the upper hole in that spindle that aren't in a kit.