>>8289656Nah, that one had a clear concept art and a few decent reference panels.
If I recall correctly, the first/original Tarn concept had the issue of Cassy Sark trying to make it a Rodimus pre-mold, resulting it it looking pretty off.
You’re probably thinking about their MTMTE Megaton, who never transformed or was shown in alt-mode once in the entire run. Though even then, ‘Spaceship/jet with treads’ was an odd interpretation for his alt-mode.