GSX always uses the long pole on the nose type of truck to push back.
No, it doesn't.
There are many different pushback *models* available, and they are chosen depending on certain conditions and, they might be or not available in different *liveries*, which are assigned depending on the airport + parking score, as explained briefly in the GSX Manual, but more in detail in the PaintKit documentation.
These models have conditions:
FSDT_Pushback - large towbarless model
FSDT_Pushback _02 - large towbar model
They both appear when the aircraft weight is > 170000 AND the parking radius is > 18 mt.
FSDT_Pushback_Small - smaller truck with a towbar, if the aircraft weight is < 170000 OR the parking radius is < 18 mt.
The other available models, don't have any conditions, which means they can always be selected, but in addition to be selectable by having satisfied a condition that selects a different *model*, the rules related to the *livery* selection, which are related to the airport and the parking code, will then specify which variant (livery) of the model will be used.
I tried to change the CFG files of the " FSDT_Pushback_TPX" however, I didn't even find a " condition" entry.
The TPX was a bit of a special case, because we didn't do it in multiple liveries, initially. So, even if it was available, it was unlikely to be seen, because it would always "lose" in score against vehicles with multiple liveries which gained an higher score because of this.
Following that thread, we updated the vehicles set so, if you download and install one of the Vehicle update installers now, or the current GSX Full installer, even the TPX model has multiple liveries, so it will have an equal chance to be selected compared to the other ones.