XC5 168 is the part number you are looking for. When I call the company, I will ask if they are the updated/revised version. They ebay version looks like it will work as well. It probably is a generic version of the same stepper motor. When I searched the web, I found lots of manf. of stepper motors. The hardest part is finding one that will work for this application. For as easy of a job it is to replace the stepper motor. I am going to try the ebay version. Just remember to be carefull of ESD (electrostatic discharge) it could damage componets on your motherboard. Also, do not use to much heat when soldering as this will damage your board. If you don't have a soldering iron, buy one with a smaller tip. You will also need soldering wick, flux and solder. The soldering wick is what you use to remove the solder from the old stepper motor. The wick is put on the terminal you want to remove on the back of the board and then the soldering iron tip rest on top of it. The heat from the soldering iron draws the solder into the soldering wick. Just make sure all the solder is gone from the terminal going thru the board before pulling off the stepper motor. Otherwise if you force the removal of the stepper motor, you will damage the board and it will be trash. When installing the new stepper motor, put a little flux on the connections your are soldering. Then put a dab of solder on the soldering iron and heat up both connections at the same time. Apply solder for about 2 seconds and it will flow onto the board and the stepper motor terminal.
If you are unsure if this will fix your problem, take the stepper motor off the voltage gauge and swap it with the stepper motor on the speedo.
All the motors are the same on the board that run the gauges. If your speedo motor is bad, the voltage gauge will be inop and the speed will work after the swap.
The hardest part taking apart the instrument panel is removing the needles from the stepper motor. I found if you turn the needles CCW they would come off easier. However, mark with a pencil where the stepper motor stops when you turn it CCW before you force the needle CCW. What you are doing is trying to mark the calibration of the gauges before you move the needles. Once the needles are off, they can go on in any position and therefore show false gauge readings. I have found when you start the truck and turn it off again the gauges go thru a zeroing process and this will help you make sure the needles are put on correctly. If someone really wanted to they could dicifer what wire controlls what gauge and apply a known voltage value and calibrate the gauges afterwords.
I hope this information helps. It really is a easy job to do. Just take your time.