I am sure that the borg warner 3 bar sensor is the correct part, the part numbers ec1678. it has a sticker identicial to the GM OEM one, with the GM part number of 12223861 on it. so it appears that borg warner is probably the supplier of this part for GM. A pic of the sensor is included , there is a slot in the B plug at the 12 O'clock position and the A plug at the 9 O'clock when holding the sensor as show in the pic. This seems correct verified by this webpage :
http://www.hhscott.com/93tmv/3-bar_map2.htm
you can get the borg warner plug from oreily's for $70.
Still looking for the correct matching plug, if anyone knows of a plug that matches the configuration of this sensor please let me know.
ROB : i believe this makes the borg warner plug the "old style", you might want to confirm and update it on your webpage.