Soft parts include clutches, bands, overhauls kit, filter, internal sealing rings, bushings, external seals and gaskets. These are the parts, along with a torque converter, that are always replaced during an overhaul of a transmission.
Upon internal inspection, some major component parts may also need to be replaced such as the pump, a clutch drum, or a planetary gear set. There’s no way to know the condition of these “hard parts” before the unit is disassembled in order to include them in an estimate.
In the “old days” the cost of these parts was minimal due to the limited variety of transmissions and could be included in the estimate, however late model, computer controlled unit can have some expensive parts that may need to be replace to insure that the unit is fully repaired.
So, it is common for a major repair of a transmission to include a list of the commonly replaced parts, and remain open until an internal inspection of the unit can be made.