MAP sensor for a 91 MGM/CP Wagon

Why would there be 2 different OE part numbers for a 1991 MAP sensor on a MGM/CP Wagon?
Since I do not know if the one on the car is correct, how do I determine which part number I would need to purchase?

Also, is the map bolted on the passenger side of the firewall just below the top edge on the 91.....

There is 1 MAP sensor OR a baro sensor. You need to determine which one your vehicle has. Call the dealer and see if they can give you the correct part.

There is 1 MAP sensor OR a baro sensor. You need to determine which one your vehicle has. Call the dealer and see if they can give you the correct part.

I did call and they told me there are 2 different numbers and cannot tell me which one I need, that is why I am asking here.....