Actually this is God Ginrai and he's not Optimus Prime. He has appeared in Transformers Master Force (1988) which sequel to G1 and Headmaster series. Ginrai (a human) transform and combine with his Truck (a transformers who is God Ginrai himself) to be the one and fought with Overlord and Devil Z. After the battle, Devil Z who has created all God Masters Transformers and comebined them with God Master Humans be destroyed, Ginrai separate with God Ginrai and God Ginrai to be himself. In USA toyline, this form was introduced as powermaster Optimus Prime
wow thats sick! nicely done man! hes actually 1 of my TOP 5 Optimus Prime characters out there ever. But I think hes my #1 fav but not sure though. I actually have the G1 Reissue Set of him, but not the real old G1 set of him when it 1st came out. But nicely done!