We only do front pump reseals on trannies with less than 100K. The rubber seals that fail all have the same life and proper repair of the front seal is about half the cost of a total repair/rebuild.
The front pump/torque convertor seal might be your problem and it only requires the tranny removal and the seal replacement. Unfortunately it is just as likely that the leak is from the large o-ring sealing the iron pump body to the aluminum trans housing. Replacing this seal is not so easy and requires disassembly of the front of the tranny. I would not do one without the other as there is no way of seeing the leak from the outside. Once inside there is oil everywhere and the labor risks of a wrong call make both seals a necessity.
If you go to that trouble for two seals, it then seems a waste to not double that amount for the other hundred or so.
Bosch Master, ASE Master, L1
33 years MB technician