This is how ROTF Optimus should've been. I've always thought that the battery unit + electronics being a total waste of space, considering how much of his back kibble can be easily tucked inside that shell.
i wish tell what i did to optimus but my english not enough to explain it basicly i open boady it is very hard specially unplug the pin and i put in the boady very long horizontal pin i attach all moveable part to it i now that is not explain anything sorry for my language