Hey there, the prestige Leviathan class items are physically identical to the regular Leviathan class items, they do not have the glowing parts that the other pieces do - they just have a different colour scheme. So they are collapsed into a single transmog choice, you can use Shadow's Cloak + Calus' Treasured to replicate the original look. This old twab mentions it. https://help.bungie.net/hc/en-us/articles/360059413251-Armor-Synthesis-Guide