That is NOT a TZ gearbox. It is a standard Giulietta 4 speed. A TZ doesn't have a cross member mount on the rear. It is held in place by a bracket with two rubber bushings that attach to the tube frame. Whoever is selling it is sadly mistaken and deluding themselves as to the value.
Yes, I owned a TZ and am very familiar with what these parts look like.
Hello Richard,Hi Olaf
Will you share the source of this foto....if possible? Then I will explain why it is interesting, for TZ trivia buffs, that is!