Here is a breakdown of the Buster Machines in Gunbuster:
- Buster Machine No. 1 = Noriko's Buster Machine
- Buster Machine No. 2 = Kazumi's Buster Machine
- Buster Machine No. 1 + 2 = Gunbuster
- Buster Machine No. 3 = Blackhole Bomb ("Jupiter-in-a-can")
- Buster Machine No. 4, 5 and 6 = Sizzler Black, White, Silver (mass-produced prototypes)
- Buster Machine No. 7 =
If you compare the original Gunbuster to Dix-Neuf, the "new" buster machines are fairly weak compared to the old ones and considerably smaller than the original Gunbuster as well.
Take note that the original machine had a full-height hatch in the side of its hand. Nono appears to be roughly as tall as Dix-Neuf's hand is wide. If Dix-Neuf and the original Gunbuster are built on similar proportions, the original would be at least two to three times the size of Dix-Neuf, not to mention considerably more powerful since it could dispatch a large number of space monsters similar to the "variable gravity well."
It's never referenced how old Dix-Neuf is, but it has an original Buster Machine cockpit, a set of the Top uniform, and is Degeneration Reactor compatible. The greatest difference between the traditional Buster Machines and the TOPLESS Buster Machines are their power sources (to bend the laws of physics). Traditional Buster Machines have a Degeneration Reactor, each with an output greater than the Sun. TOPLESS Buster Machines are powered by their TOPLESS.
By grabbing a Degenerating Reactor from a Buster Corp unit, Dix-Neuf becomes Buster Machine No. 19, so it never was the original Gunbuster.