Hi David,

I'm no expert in tranny, but to my knowledge, there is no tranny speed sensor. There is engine speed sensor that is mounted between the engine and tranny and it has nothing to do with the clunk,
The possibility is that your tranny has gone bad. can be the seals, the valve body or the clutches..
You would get a blinking arrow if your Gear Position Switch gone bad.
The ABS speed sensor you mentioned on your previous posting are the ones mounted on your wheels (4 units). They are connected with wires to each wheel, so you just find the wire and you will find the sensor. The ones in front can be easily detached. Again, to me, those sensors do not contribute to the clunk. Your ABS mil will lit and your Speedometer will fail when there is something wrong with the ABS or the sensors.
Some would suggest tranny flush but when flushing won't do, I suggest you start searching for tranny rebuild kit and garage who is able to do the job.