DinoLast
Super Freak
Actually I'd say the Mark II of this movie is the Mark V. The Mark IV is the starter piece just like the Mark I is. The Mark II was the transitional and for all intents and purposes it looks like the Mark V is the transitional as well. It still might be last but remember HT loves to redo things if they can. With the articulated waist and the movable fingers I could see them doing the Mark IV to add the new tech like they did with the Batman Original Costume from The Dark Knight. Its fairly close to the Mark III with only cosmetic differences.
I think the difference between the MK V and any other mark in the two movies, is that it's not been made to replace the previous suits. I would assume Stark had it as back up while he was still using the MK IV