The '73 if I'm not mistaken has a taller spindle than your 69 or 66. It can be used , however They also require use of aftermarket upper A-arms in most cases, as there's not enough room for shims to align it properly on 64-67s, or if you have a bigblock or headers on a 68-72.I have a 69 and a 66 elcamino,i found a junkyard with a dozen 73 and up parts cars will the disc brake assemblies fit either ,or both of my cars?