>>7446713The chest doors are the primary difference on the body.
Japanese Overlord was from the Masterforce cartoon, where there were barely really any true Cybertronians and instead a heavy focus on humans. Transtectors are Cybertronian bodies that tiny Cybertronians or human/Cybertronian hybrids like Mega and Giga or ordinary kids with divine magic bracers can control or become a power source for.
Mega and Giga would take turns, one controlling the body and one as the power-up, and outside of battle the body became their home in base mode. I think Mega, the male one on the left in pic related piloted the tank, and Giga on the right piloted the jet.
I say all this to explain the doors. For the modern toy Mega and Giga have masculine and feminine faces on their backs as Headmasters rather than as power engines like in the original toy. So whichever one isn’t the current head is stored in the corresponding door behind the one that matches their original figure, pic related.
You can emulate this cheaply with the Shapeways door covers that just clip on over the American Overlord doors, and the male and female replacement heads. Or just the female one, and use America Overlord’s as the masculine one. Or buy both and the Shapeways IDW style one with the thick lips. Up to you.