This mod was a german fan-project called Tower Defense: Trinity Force for C&C Generals Zero Hour...
The Overheader's origin is the Overlord-tower
of TD:TTK. The Overheader has now two jobs: its
main task is to stop tanks with anti-tank
projectiles, but special modifications after the
upgrade allow you to use an medium-effective
anti-infantry minigun as well.
great idea with the minigun, but dont you think that the Overheader might become overpowered then?
No. The minigun is not as effective as real anti-infantry weapons like Toxin Sprinkler or Vulcan Gun, and you can either use the Overheader's anti-tank OR minigun-weapon, not both at the same time.
So it works just fine with balancing.
just play the TDTF demo. the Overheader is already in there. :)