He seems to be missing his little 'boots'.
I'm not really an expert on Diaclone, but I would guess that he belonged to the red Sunstreaker, maybe. I know that toy found its way around the world under various guises.
The multi-vehicle combiner robots were made under license by a few manufacturers, too. Some of these probably came with little men. Do you remember owning lots of non-transforming vehicles that combined?