One is in the front of the transmission case, down on the passenger side(input speed code 2214)), the Turbine sensor code 2215 is in the valve module inside the transmission and that whole module must be dropped to access that sensor. The output speed sensor(code 2216) is in the transfer case, you must drain the Tcase oil and it is under the cover plate on the rear middle/passenger side of center, (senses the middle gear in the Tcase). Its connector, shared with the 4x4 difflock signal is on the front of the transfer case…
since it is a turbine code and that one is the most difficult to access, I would start by going hand over hand on every inch of wiring and check every connector between the transmission Control Unit in the cab and the connection down into the valve module on the passenger side of the transmission…
you can do ohm tests on the sensors, that procedure and the specifications are in the MD3060(covers MD3070PT trans) troubleshooting manual.
Google TS2470EN and you can download it from many locations. Not sure if it is available here in the manuals section on SS, never looked for it…
Good Luck!