Sunstreaker's original body is not seen again after Escalation issue 1. In Devastation 2, Hunter encountered his real head, who begged the human to put him out of his misery lest he bring more harm to the Autobots.

Hunter asked to become a Headmaster, Sunstreaker warned him the process would hurt. Afterwards, Sunstreaker's real head was slack-jawed and non-responsive. At roughly the same time, the Sunstreaker clones fighting Hot Rod suddenly lose control and are easily defeated.

(My interpretation is Sunstreaker put nearly all of his conciousness into Hunter so he could get the hell out of there.)

Sunstreaker's reflexes take over when they are discovered, and they steal one of the many fabricated Sunstreaker bodies to make their escape. It should be noted that when Hunter transforms, he turns into Sunstreaker's normal head, not the more mechanical-looking red-eyed Machination head. Obviously this was done so you could easily tell who was the real Sunstreaker.