1.7.3 .Java Models importing and using

I want to make 3D armor for Minecraft 1.7.10, in the resources section of mcreator 1.7.3 does not have any options to import .java models... How can I do this, if not possible in this mcreator version is there an alternative like changing the mcreator version and using a plugin for 1.7.10 / converting (downgrading a mod to 1.7.10)