Where Does It Go?

I have an '87 GM and my cousin gave me a part for it (left over from his car but the part is new). The Motorcraft Part Number is YG-337. It is a A/C Vacuum Valve part but I would like to know EXACTLY where it is, on the car? A diagram or photo would be great. Many thanks....MB

If this is it, look on the firewall to the center area of the engine. If so, it is a vacuum check valve to keep vacuum in the a/c system to keep your doors from closing at the wrong time. If it is not on the firewall area, look above the accelerator pedal.

http://usera.imagecave.com/way2old/MERCAC.jpg

Yes, that is the correct part and it was just where you said it would be - just off the firewall "T". I put it in yesterday but will not be using the car for a while so I'll post if there are any problems. Can you take a look at the post I wrote about NO HEAT IN '87 GM?? Many thanks for your helpful info!! MB