The speed sensor is on the conductor plate so that needs replaced. While you are doing this also replace transmission adaptor plug (these leak overtime). Inspect the cables from the plug to see if transmission fluid is seeping into them.
The trans fluid can travel up these cables into the TCU. If this has happened, you can try to clean the TCU with electrical cleaner but more than likely will have to replace TCU. You can order kits that come with conductor plate, filter, gasket and adaptor. A complete rebuild of the transmission at this point tells me you need to find a new transmission shop.