There are different wings depending on the year model of the car. If the car is Alt1.dds then 2016 wing is Alt1Wing.dds, 2017 wing is Alt1Extra7.dds and 2018 wing is Alt1Extra8.dds.
You don't really need to pack these in a .mas file, if you have the names right it will work. Although it is good practice to make a .mas file