Need a Part # for Vacuum Switch

I need the part number or an image or link to an online retailer that sells the vaccum switch for my 98 4WD.

The people at Napa quoted me $36 but I thought it was around $50 so I want to make sure they are quoting me the correct one.

The switch on top of the transfer case?

http://www.napaonline.com/cgi-bin/ncommerce3/ExecMacro/NAPAonline/search_results_product_detail.d2w/report?prrfnbr=23485995&prmenbr=5806&usrcommgrpid=78325205

I don't think that is it. I need the piece that the 2 vaccum hoses go into. That is the piece that usually goes bad if your 4wd doesn't engage right?

That is the unit that has the two vacuum hose ports on it.

My eyesight must be shot because I can't make out a second hose port.

This switch has three ports. It screws into the top of the transfer case. Is that the switch that you need?

I apologize for my error. I replaced this "switch" just not too long ago due to the ball sticking, and I apparently can't recall the proper number of ports it had. I had thought it had 2 ports and 1 small stud to prevent the vacuum harness "plug" from being put on in a different spot onto the switch.

Yes I need that one.

I have a 2000 blazer 4x4 with the 4.3.... I have recently notice a power loss and poor gas milage. I have replaced all the vacuum lines that the eye can see and found 1 that had a huge hole in it. I connected my vacuum gauge and it reads 15 at idle and 20 when it's accelerated. Is this the correct spec or should I check for more leaks?. Thanks Don