Speedometer quits working and the sensor has been

The sensor in the differential is for the ABS. Did you replace the sensor for the speedometer in the end of the transmission?
And is the check engine light on ?

its located on transfer case rear end near propeller shaft , have 3 wires plug

Well you know it does not have a speedo cable since you replaced the speed sensor in the transmission.
My guess would be a problem with the speedo or cluster.

sounds like a faulty speed sensor check you electrical connections at the sensors as well as the transmission is the check engine lite on

Speedometer cable needs replaced. It is very easy to do if you have a little common sense and a few common tools.
The cable runs from the speedometer to the transmission, Just purchase a new speedo cable and remove the instrument cluster, Look at the backside of the cluster to find the cable to the speedometer, Remove it as you follow the cable to trans replace the same way it was removed and reinstall cluster.

The odometer quits working when the speedometer quits working. The most common cause for the speedometer to quit working is the speed sensor in the transmission. You said you replaced it, there is also a transmission speed sensor on your truck that may need to be replaced. I understand your frustration, but there is nothing else that would cause the speedometer to quit except the cable behind the gauges being clogged.

Check your cable it might be snapping then if thats not the case your gear might be bad that would be in your gear transmission goto http://www.buzzle.com/articles/speedometer-not-working-properly.html for more info

You need to replace the speedometer gear that drives the sensor.

first of all, the power steering pump doesn't stop working and then start working usually they are just bad. second of all it shouldn't take 3 hrs to change speed sensor, and last the vss could cause all symptoms, if the car has variable assist steering the speed sensor could effect this

Try replacing the speedometer sensor, located on the transmission under the car. There will be a few wires going to it with a plug. The speed sensor is a retivly low cost part, and most of the time when it begins to quit it will give irratic readings on the dash.
Hope this helps!