The trans would be disassembled enough to get to the reverse clutches, they would be replaced along with a couple of internal / external seals, filter. None of the other clutches / bands would be changed or inspected. This would make reverse work again but all of the other parts would be suspect.

A full rebuild consists full disassembly , all / most friction material replaced , any worn bushings , all internal and external seals, some "hard parts" if needed plus sometimes valve body repairs for areas prone to wear.