Tamiya has, to my knowledge, 4 Gearbox Systems:
- the vintage 1 motor 2 clutch one
- the legacy 2 motor 2 gearbox one
- the modern 2 motor 1 gearbox one 💖
- the revised 2 motor 2 gearbox one
Based on my collection of Tamiya Tank Assembly Manual PDFs it appears that
only the M26 Pershing is using the upper Shaft output location arrangement of the legacy gearbox system while every other tank is using the bottom one.
You probably got shafted by the economies of scale 🤣