ok im confused, which is the mk5 and mk6? Is the mk6 the silver centurian briefcase one?
The Mark 4 - the new suit with circular chestpiece( skydive scene)
The Mark 5 - The portable silver and red briefcase armor
The Mark 6 - Essentially its the upgraded Mark 4, it has a triangle chestpiece with some silver bits in places.
The marks are basically given there numbers by the order they appear in the film.