you must change out the tourqe converter or hydrolic kit on trans.
May have to take it to a certified speedometer repair shop
Inside the transmission attached to the valve body, under the trans pan, which must be removed to gain access.
I was told by my mechanic (who I trust implicitly, very honest) that you have to drop the engine and transaxle out of the car as a unit which makes it very labor intensive and expensive by racking up...
th-200c. 200 metric. turbo-hydramatic 200. whatever the name, they are all the same.
the flasher is on the right side under the glove box.