Are there more pirate M6's in assassin missions?

[Reliku]

Hi

so I have finally graduated X2 and X3R, and am now playing an unmodified X3TC on steam, anyhow I am noticing that when I get assassin missions worth anywhere from 1-3 mil reward, they either spawn pirate centaur, ospery, or a M8 bomber. I had saved and reloaded some of these before calling the station for the mission, to see if there are any variations, but it is always cycling between those 3. On the 4 mil+ reward I occassionaly get a carrack. What happened to the dragon or nemesis? Do they ever show up?

running Poisoned Paranid start game, got the hype if that makes any differece.

[Rogue]

While I've seen other Pirate m6 variants about (Heavy Hydra/Nemesis) I've never had one on an assassination mission. Should be possible though

[Triaxx2]

Dragon's and Nemesis usually only show up with non-mission pirates.