I just replaced mine.
$23.00 and change at the local Auto parts store.
Driver's side of the trans.

TIP:
Use a drain pan when changing.
Unscrew almost all the way out.
Have the 2nd sensor in your other hand, and swap them REAL quick and you'll only lose about 1/4 cup of tranny fluid.

We'll see if that 1st shift goes OK after it's cooled off.
It's been hanging in 1st until I let off the accelerator, but ONLY on the 1st shift after start-up.
After that 1st one, it shifted fine.

Is it just me, or do these trucks all seem to want to puke parts in groups?
Bunches of VPs dieing all at once, Speed Sensors, Lift Pumps, .......
It's kinda like going to a restaurant with several couples and all the ladies going to the Restroom at the same time.

 

Several people have stated that their output shaft speed sensor is on the driver's or left side of the transmission. mine is on the right side and I am wondering if these sensors are different for different model years. My truck is a 98.5 and is on the right side, just in front of the cross member. Please advise where it is located on your model truck.

Daniel

 

I used a 1" deepwell socket to remove it.



click on the smaller picture to enlarge

 

mine is a 98.5 and is on the drivers side of the transmission near the rear.
output speed sensor or something like that

I believe autozone just called it the speed sensor without distinguising which one.

 

By the way,
I was parked slightly downhill,....and I didn't loose more than about 10 drops of ATF when I changed it.

 

UPDATE:
Truck is shifting perfectly again.
1st to 2nd after startup is around 1700 rpm again.

My Auto Parts place called it a Transmission Speed Sensor.