GM has 1,2,and 3 bar MAP sensors that are OEM on their products. The MAP part numbers (not complete):
3 digit numbers for identification:
1 Bar: 039, 460, 883, 876, 153, 719 (green connector?)
2 Bar: 886, 012, 539, 609, 701, 539 (tan connector?)
3 Bar: 749, 861
The 2 and 3 BAR sensors have a unique key system in the connector. If the center socket has a vertical key in it, its a 2 or 3 BAR sensor. If there is no key in the center socket its a 1 BAR. Orientation when mounting is important. Mount so the nipple is facing <30 degrees from down so as to prevent moisture from pooling from condensation. Also recommended to mount higher than intake. I found a 2 BAR MAP on a supercharged Pontiac Bonneville. They are not that uncommon in US junkyards. Its mounted right behind the supercharger on a bracket, just follow the hard pressure line from under the pulley and is held on by a T20 torx bolt but a good pair of pliers can grip the bolt and unscrew as the torque spec is low to prevent deformation of the case.
This is example of "no key" 1 BAR sensor socket. Suitable for all reference external MAP sensors