Thanks guys, today during nap time , I am going to take one of the batteries out because the battery pack is to tall to let his head go down to transform.
Funny anecdote about this mod.. During the dremiling of Optimus's head , my son , says
"Dadda you watch out for Mac Prime's brain... oooh watch out..."(all nervous) (he calls optimus mac pirme.) He hovered over me watching making sure I did not mess up Optimus's brain.