The Crystal RX-78-2 is based on the MG RX-78-2 1.0 release--and really doesn't have an "inner frame" to speak of (aside from the torso, backpack, and top of the head). As such, there's probably not going to be a real easy way to make the crystal shell fit over the 1.5 RX-78-2. I'm not saying it can't be done, but it would probably require some hefty modification.