2001 alero 3.4liter. Check engine light on and the code were read at autuzone. Vacumn leak and tranmisson speed sensor. The alero shift hard after about a hour of driving Bought speed sensor but can not find it. Maybe thats not it.

The vehicle speed sensor (VSS) is located at the transaxle extension housing on the passenger side where the axle shaft inserts. Also, you will see a lone wiring harness to it.

And welcome to AF.

Is it inside the transmission or external. Thank you. Also the low tire air pressure light is also on. Does that mean anything.

External. If you look carefully in the area described you will see it. Check your tire pressure (all four) or maybe it just needs to be reset if all four tires have normal air pressure.

There two different transmisson sensor. Ouput is the one you told me the location. There is also a input sensor.